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  • Why are emails sent from my applications being marked as spam?

    - by Brian
    Hi. I have 2 web apps running on the same server. The first is www.nimikri.com and the other is www.hourjar.com. Both apps share the same IP address (75.127.100.175). My server is through a shared hosting company. I've been testing my apps, and at first all my emails were being delivered to me just fine. Then a few days ago every email from both apps got dumped into my spam box (in gmail and google apps). So far the apps have just been sending emails to me and nobody else, so I know people aren't manually flagging them as spam. I did a reverse DNS lookup for my IP and the results I got were these: 100.127.75.in-addr.arpa NS DNS2.GNAX.NET. 100.127.75.in-addr.arpa NS DNS1.GNAX.NET. Should the reverse DNS lookup point to nimikri.com and hourjar.com, or are they set up fine the way they are? I noticed in the email header these 2 lines: Received: from nimikri.nimikri.com From: Hour Jar <[email protected]> Would the different domain names be causing gmail to think this is spam? Here is the header from one of the emails. Please let me know if any of this looks like a red flag for spam. Thanks. Delivered-To: [email protected] Received: by 10.231.157.85 with SMTP id a21cs54749ibx; Sun, 25 Apr 2010 10:03:14 -0700 (PDT) Received: by 10.151.130.18 with SMTP id h18mr3056714ybn.186.1272214992196; Sun, 25 Apr 2010 10:03:12 -0700 (PDT) Return-Path: <[email protected]> Received: from nimikri.nimikri.com ([75.127.100.175]) by mx.google.com with ESMTP id 28si4358025gxk.44.2010.04.25.10.03.11; Sun, 25 Apr 2010 10:03:11 -0700 (PDT) Received-SPF: neutral (google.com: 75.127.100.175 is neither permitted nor denied by best guess record for domain of [email protected]) client-ip=75.127.100.175; Authentication-Results: mx.google.com; spf=neutral (google.com: 75.127.100.175 is neither permitted nor denied by best guess record for domain of [email protected]) [email protected] Received: from nimikri.nimikri.com (localhost.localdomain [127.0.0.1]) by nimikri.nimikri.com (8.14.3/8.14.3) with ESMTP id o3PH3A7a029986 for <[email protected]>; Sun, 25 Apr 2010 12:03:11 -0500 Date: Sun, 25 Apr 2010 12:03:10 -0500 From: Hour Jar <[email protected]> To: [email protected] Message-ID: <[email protected]> Subject: [email protected] has invited you to New Event MIME-Version: 1.0 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit

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  • Maven: Unresolved references to [org.osgi.service.http]

    - by Simone Vellei
    I'm trying to create a bundle using HttpService for register Servlet using maven-bundle-plugin. The pom.xml of the project is: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>felix-tutorial</groupId> <artifactId>example-1</artifactId> <version>1.0</version> <packaging>bundle</packaging> <name>Apache Felix Tutorial Example 1</name> <description>Apache Felix Tutorial Example 1</description> <!-- Build Configuration --> <build> <plugins> <plugin> <groupId>org.apache.felix</groupId> <artifactId>maven-bundle-plugin</artifactId> <extensions>true</extensions> <configuration> <instructions> <Bundle-SymbolicName>${pom.groupId}.${pom.artifactId}</Bundle-SymbolicName> <Bundle-Name>Service listener example</Bundle-Name> <Bundle-Description>A bundle that displays messages at startup and when service events occur</Bundle-Description> <Bundle-Vendor>Apache Felix</Bundle-Vendor> <Bundle-Version>1.0.0</Bundle-Version> <Bundle-Activator>tutorial.example1.Activator</Bundle-Activator> <Import-Package>org.osgi.framework;version="1.0.0", javax.servlet, javax.servlet.http</Import-Package> </instructions> </configuration> </plugin> </plugins> </build> <!-- Dependecies Management --> <dependencies> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.framework</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.http.api</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.http.base</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.http.bridge</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.http.bundle</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.http.proxy</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.apache.felix.http.whiteboard</artifactId> <version>2.0.4</version> </dependency> <dependency> <groupId>org.osgi</groupId> <artifactId>osgi_R4_compendium</artifactId> <version>1.0</version> </dependency> </dependencies> </project> "mvn install" command returns the following error: [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building Apache Felix Tutorial Example 1 [INFO] task-segment: [install] [INFO] ------------------------------------------------------------------------ Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-resources-plugin/2.3/maven-resources-plugin-2.3.pom Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-resources-plugin/2.3/maven-resources-plugin-2.3.jar Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-install-plugin/2.2/maven-install-plugin-2.2.pom Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-install-plugin/2.2/maven-install-plugin-2.2.jar Downloading: http://repo1.maven.org/maven2/org/apache/maven/shared/maven-filtering/1.0-beta-2/maven-filtering-1.0-beta-2.pom Downloading: http://repo1.maven.org/maven2/org/codehaus/plexus/plexus-interpolation/1.6/plexus-interpolation-1.6.pom Downloading: http://repo1.maven.org/maven2/org/codehaus/plexus/plexus-interpolation/1.6/plexus-interpolation-1.6.jar Downloading: http://repo1.maven.org/maven2/org/apache/maven/shared/maven-filtering/1.0-beta-2/maven-filtering-1.0-beta-2.jar [INFO] [resources:resources {execution: default-resources}] [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory C:\eclipse\ws\stripes-bundle\src\main\resources [INFO] [compiler:compile {execution: default-compile}] [INFO] Nothing to compile - all classes are up to date [INFO] [resources:testResources {execution: default-testResources}] [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory C:\eclipse\ws\stripes-bundle\src\test\resources [INFO] [compiler:testCompile {execution: default-testCompile}] [INFO] Nothing to compile - all classes are up to date [INFO] [surefire:test {execution: default-test}] [INFO] Surefire report directory: C:\eclipse\ws\stripes-bundle\target\surefire-reports ------------------------------------------------------- T E S T S ------------------------------------------------------- Running com.beanopoly.stripes.AppTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.031 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 [INFO] [bundle:bundle {execution: default-bundle}] [ERROR] Error building bundle felix-tutorial:example-1:bundle:1.0 : Unresolved references to [org.osgi.service.http] by class(es) on the Bundle-Classpath[Jar:do [ERROR] Error(s) found in bundle configuration [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Error(s) found in bundle configuration [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 12 seconds [INFO] Finished at: Sat Mar 27 13:11:47 CET 2010 [INFO] Final Memory: 12M/21M [INFO] ------------------------------------------------------------------------

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  • C# Begin/EndReceive - how do I read large data?

    - by ryeguy
    When reading data in chunks of say, 1024, how do I continue to read from a socket that receives a message bigger than 1024 bytes until there is no data left? Should I just use BeginReceive to read a packet's length prefix only, and then once that is retrieved, use Receive() (in the async thread) to read the rest of the packet? Or is there another way? edit: I thought Jon Skeet's link had the solution, but there is a bit of a speedbump with that code. The code I used is: public class StateObject { public Socket workSocket = null; public const int BUFFER_SIZE = 1024; public byte[] buffer = new byte[BUFFER_SIZE]; public StringBuilder sb = new StringBuilder(); } public static void Read_Callback(IAsyncResult ar) { StateObject so = (StateObject) ar.AsyncState; Socket s = so.workSocket; int read = s.EndReceive(ar); if (read > 0) { so.sb.Append(Encoding.ASCII.GetString(so.buffer, 0, read)); if (read == StateObject.BUFFER_SIZE) { s.BeginReceive(so.buffer, 0, StateObject.BUFFER_SIZE, 0, new AyncCallback(Async_Send_Receive.Read_Callback), so); return; } } if (so.sb.Length > 0) { //All of the data has been read, so displays it to the console string strContent; strContent = so.sb.ToString(); Console.WriteLine(String.Format("Read {0} byte from socket" + "data = {1} ", strContent.Length, strContent)); } s.Close(); } Now this corrected works fine most of the time, but it fails when the packet's size is a multiple of the buffer. The reason for this is if the buffer gets filled on a read it is assumed there is more data; but the same problem happens as before. A 2 byte buffer, for exmaple, gets filled twice on a 4 byte packet, and assumes there is more data. It then blocks because there is nothing left to read. The problem is that the receive function doesn't know when the end of the packet is. This got me thinking to two possible solutions: I could either have an end-of-packet delimiter or I could read the packet header to find the length and then receive exactly that amount (as I originally suggested). There's problems with each of these, though. I don't like the idea of using a delimiter, as a user could somehow work that into a packet in an input string from the app and screw it up. It also just seems kinda sloppy to me. The length header sounds ok, but I'm planning on using protocol buffers - I don't know the format of the data. Is there a length header? How many bytes is it? Would this be something I implement myself? Etc.. What should I do?

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  • Address book with C programming; cannot compile my code.

    - by osabri
    I've divided my code into small programs so it can be easy to excute /* ab_error.c : in case of errors following messages will be displayed */ #include "adressbook.h" static char *errormsg[] = { "", "\nNot enough space on disk", "\nCannot open file", "\nCannot read file", "\nCannot write file" }; void check(int error) { switch(error) { case 0: return; case 1: write_file(); case 2: case 3: case 4: system("cls"); fputs(errormsg[error], stderr); exit(error); } } 2nd /* ab_fileio.c : functions for file input/output */ #include "adressbook.h" static char ab_file[] = "ADRESSBOOK.DAT"; //file to save the entries int read_file(void) { int error = 0; FILE *fp; ELEMENT *new_e, *last_e = NULL; DATA buffer; if( (fp = fopen(ab_file, "rb")) == NULL) return -1; //no file found while (fread(&buffer, sizeof(DATA), 1, fp) == 1) //reads one list element after another { if( (new_e = make_element()) == NULL) { error = 1; break; //not enough space } new_e->person = buffer; //copy data to new element new_e->next = NULL; if(hol.first == NULL) //list is empty? hol.first = new_e; //yes else last_e->next = new_e; //no last_e = new_e; ++hol.amount; } if( !error && !feof(fp) ) error = 3; //cannot read file fclose(fp); return error; } /*-------------------------------*/ int write_file(void) { int error = 0; FILE *fp; ELEMENT *p; if( (p = hol.first) == NULL) return 0; //list is empty if( (fp = fopen(ab_file, "wb")) == NULL) return 2; //cannot open while( p!= NULL) { if( fwrite(&p->person, sizeof(DATA), 1, fp) < 1) { error = 4; break; //cannot write } p = p->next; } fclose(fp); return error; } 3rd /* ab_list.c : functions to manipulate the list */ #include "adressbook.h" HOL hol = {0, NULL}; //global definition for head of list /* -------------------- */ ELEMENT *make_element(void) { return (ELEMENT *)malloc( sizeof(ELEMENT) ); } /* -------------------- */ int ins_element( DATA *newdata) { ELEMENT *new_e, *pre_p; if((new_e = make_element()) == NULL) return 1; new_e ->person = *newdata; // copy data to new element pre_p = search(new_e->person.family_name); if(pre_p == NULL) //no person in list { new_e->next = hol.first; //put it to the begin hol.first = new_e; } else { new_e->next = pre_p->next; pre_p->next = new_e; } ++hol.amount; return 0; } int erase_element( char name, char surname ) { return 0; } /* ---------------------*/ ELEMENT *search(char *name) { ELEMENT *sp, *retp; //searchpointer, returnpointer retp = NULL; sp = hol.first; while(sp != NULL && sp->person.family_name != name) { retp = sp; sp = sp->next; } return(retp); } 4th /* ab_screen.c : functions for printing information on screen */ #include "adressbook.h" #include <conio.h> #include <ctype.h> /* standard prompts for in- and output */ static char pgmname[] = "---- Oussama's Adressbook made in splendid C ----"; static char options[] = "\ 1: Enter new adress\n\n\ 2: Delete entry\n\n\ 3: Change entry\n\n\ 4: Print adress\n\n\ Esc: Exit\n\n\n\ Your choice . . .: "; static char prompt[] = "\ Name . . . .:\n\ Surname . . :\n\n\ Street . . .:\n\n\ House number:\n\n\ Postal code :\n\n\ Phone number:"; static char buttons[] = "\ <Esc> = cancel input <Backspace> = correct input\ <Return> = assume"; static char headline[] = "\ Name Surname Street House Postal code Phone number \n\ ------------------------------------------------------------------------"; static char further[] = "\ -------- continue with any key --------"; /* ---------------------------------- */ int menu(void) //show menu and read user input { int c; system ("cls"); set_cur(0,20); puts(pgmname); set_cur(6,0); printf("%s", options); while( (c = getch()) != ESC && (c < '1' || c > '4')) putch('\a'); return c; } /* ---------------------------------- */ int print_adr_book(void) //display adressbook { int line = 1; ELEMENT *p = hol.first; system("cls"); set_cur(0,20); puts(pgmname); set_cur(2,0); puts(headline); set_cur(5,0); while(p != NULL) //run through list and show entries { printf("%5d %-15s ",line, p->person.family_name); printf("%-12s %-15s ", p->person.given_name, p->person.street); printf("%-4d %-5d %-12d\n",p->person.house_number, p->person.postal_code, p->person.phone); p = p->next; if( p == NULL || ++line %16 == 1) //end of list or screen is full { set_cur(24,0); printf("%s",further); if( getch() == ESC) return 0; set_cur(5,0); scroll_up(0,5,24);//puts(headline); } } return 0; } /* -------------------------------------------*/ int make_entry(void) { char cache[50]; DATA newperson; ELEMENT *p; while(1) { system("cls"); set_cur(0,20); puts(pgmname); set_cur(6,0); puts("Please enter new data:"); set_cur(10,0); puts(prompt); set_cur(24,0); printf("%s",buttons); balken(10, 25, MAXL, ' ',0x70); //input name if(input(newperson.family_name, MAXL, ESC, CR) == ESC) return 0; balken(12,25, MAXL, ' ', 0x70); //surname if(input(newperson.given_name, MAXL, ESC, CR) == ESC) return 0; balken(14,25, 30, ' ', 0x70); //street if(input(newperson.street, 30, ESC, CR) == ESC) return 0; balken(16,25, 4, ' ',0x70); //housenumber if(input(cache, 4, ESC, CR) == ESC) return 0; newperson.house_number = atol(cache); //to string balken(18,25, 5, ' ',0x70); //postal code if(input(cache, 5, ESC, CR) == ESC) return 0; newperson.postal_code = atol(cache); //to string balken(20,25, 20, ' ',0x70); //phone number if(input(cache, 20, ESC, CR) == ESC) return 0; newperson.phone = atol(cache); //to string p = search(newperson.phone); if( p!= NULL && p->person.phone == newperson.phone) { set_cur(22,25); puts("phonenumber already exists!"); set_cur(24,0); printf("%s, further"); getch(); continue; } } } 5th /* adress_book_project.c : main program to create an adressbook */ /* copyrights by Oussama Sabri, June 2010 */ #include "adressbook.h" //project header file int main() { int rv, cmd; //return value, user command if ( (rv = read_file() ) == -1) // no data saved yet rv = make_entry(); check(rv); //prompts an error and quits program on disfunction do { switch (cmd = menu())//calls menu and gets user input back { case '1': rv = make_entry(); break; case '2': //delete entry case '3': //changes entry rv = change_entry(cmd); break; case '4': //prints adressbook on screen rv = print_adr_book(); break; case ESC: //end of program system ("cls"); rv = 0; break; } }while(cmd!= ESC); check ( write_file() ); //save adressbook return 0; } 6th /* Getcb.c --> Die Funktion getcb() liefert die naechste * * Tastatureingabe (ruft den BIOS-INT 0x16 auf). * * Return-Wert: * * ASCII-Code bzw. erweiterter Code + 256 */ /* Hinweis: Es muss ein DOS-Compiler verwendet werden. * * (z.B. der GNU-Compiler fuer DOS auf der CD) */ #include <dos.h> int getcb(void) { union REGS intregs; intregs.h.ah = 0; // Subfunktion 0: ein Zeichen // von der Tastatur lesen. int86( 0x16, &intregs, &intregs); if( intregs.h.al != 0) // Falls ASCII-Zeichen, return (intregs.h.al); // dieses zurueckgeben. else // Sonst den erweiterten return (intregs.h.ah + 0x100); // Code + 256 } 7th /* PUTCB.C --> enthaelt die Funktionen * * - putcb() * * - putcb9() * * - balken() * * - input() * * * * Es werden die Funktionen 9 und 14 des Video-Interrupts * * (ROM-BIOS-Interrupt 0x10) verwendet. * * * * Die Prototypen dieser Funktionen stehen in BIO.H */ /* Hinweis: Es muss ein DOS-Compiler verwendet werden. * * (z.B. der GNU-Compiler fuer DOS auf der CD) */ #include <dos.h> #define VIDEO_INT 0x10 /*---------------------------------------------------------------- * putcb(c) gibt das Zeichen auf der aktuellen Cursor-Position * am Bildschirm aus. Der Cursor wird versetzt. * Steuerzeichen Back-Space, CR, LF und BELL werden * ausgefuehrt. * Return-Wert: keiner */ void putcb(unsigned char c) /* Gibt das Zeichen in c auf */ { /* den Bildschirm aus. */ union REGS intregs; intregs.h.ah = 14; /* Subfunktion 14 ("Teletype") */ intregs.h.al = c; intregs.h.bl = 0xf; /* Vordergrund-Farbe im */ /* Grafik-Modus. */ int86(VIDEO_INT, &intregs, &intregs); } /*---------------------------------------------------------------- * putcb9(c,count,mode) gibt das Zeichen in c count-mal im * angegebenen Modus auf der aktuellen * Cursor-Position am Bildschirm aus. * Der Cursor wird nicht versetzt. * * Return-Wert: keiner */ void putcb9( unsigned char c, /* das Zeichen */ unsigned count, /* die Anzahl */ unsigned mode ) /* Low-Byte: das Atrribut */ { /* High-Byte: die Bildschirmseite*/ union REGS intregs; intregs.h.ah = 9; /* Subfunktion 9 des Int 0x10 */ intregs.h.al = c; intregs.x.bx = mode; intregs.x.cx = count; int86( VIDEO_INT, &intregs, &intregs); } /*---------------------------------------------------------------- * balken() positioniert den Cursor und zeichnet einen Balken, * wobei Position, L„nge, Fllzeichen und Attribut * als Argumente bergeben werden. * Der Cursor bleibt auf der ersten Position im Balken. */ void balken( unsigned int zeile, /* Start-Position */ unsigned int spalte, unsigned int laenge, /* Laenge des Balkens */ unsigned char c, /* Fuellzeichen */ unsigned int modus) /* Low-Byte: Attribut */ /* High-Byte: Bildschirmseite */ { union REGS intregs; intregs.h.ah = 2; /* Cursor auf der angegebenen */ intregs.h.dh = zeile; /* Bildschirmseite versetzen. */ intregs.h.dl = spalte; intregs.h.bh = (modus >> 8); int86(VIDEO_INT, &intregs, &intregs); putcb9(c, laenge, modus); /* Balken ausgeben. */ } /*---------------------------------------------------------------- * input() liest Zeichen von der Tastatur ein und haengt '\0' an. * Mit Backspace kann die Eingabe geloescht werden. * Das Attribut am Bildschirm bleibt erhalten. * * Argumente: 1. Zeiger auf den Eingabepuffer. * 2. Anzahl maximal einzulesender Zeichen. * 3. Die optionalen Argumente: Zeichen, mit denen die * Eingabe abgebrochen werden kann. * Diese Liste muá mit CR = '\r' enden! * Return-Wert: Das Zeichen, mit dem die Eingabe abgebrochen wurde. */ #include <stdarg.h> int getcb( void); /* Zum Lesen der Tastatur */ int input(char *puffer, int max,... ) { int c; /* aktuelles Zeichen */ int breakc; /* Abruchzeichen */ int nc = 0; /* Anzahl eingelesener Zeichen */ va_list argp; /* Zeiger auf die weiteren Arumente */ while(1) { *puffer = '\0'; va_start(argp, max); /* argp initialisieren */ c = getcb(); do /* Mit Zeichen der Abbruchliste vergleichen */ if(c == (breakc = va_arg(argp,int)) ) return(breakc); while( breakc != '\r' ); va_end( argp); if( c == '\b' && nc > 0) /* Backspace? */ { --nc; --puffer; putcb(c); putcb(' '); putcb(c); } else if( c >= 32 && c <= 255 && nc < max ) { ++nc; *puffer++ = c; putcb(c); } else if( nc == max) putcb('\7'); /* Ton ausgeben */ } } 8th /* Video.c --> Enthaelt die Funktionen * cls(), * scroll_up(), scroll_down(), * set_cur(), get_cur(), * set_screen_page(), get_screen_page() * * Die Prototypen dieser Funktionen befinden sich in BIO.H */ /* Hinweis: Es muss ein DOS-Compiler verwendet werden. * * (z.B. der GNU-Compiler fuer DOS auf der CD) */ #include <dos.h> #include "bio.h" #define VIDEO_INT 0x10 typedef unsigned char BYTE; void scroll_up( int anzahl, int anf_zeile, int end_zeile) { /* Fenster hoch rollen. */ union REGS intregs; intregs.x.ax = 0x600 + anzahl; /* Subfunktion AH = 6, */ /* AL = Anzahl Zeilen. */ intregs.x.cx = anf_zeile << 8; /* CH=anf_zeile, cl=0 */ intregs.x.dx = (end_zeile <<8) | 79; /* DH=end_zeile,DL=79 */ intregs.h.bh = 7; /* normales Attribut */ int86(VIDEO_INT, &intregs, &intregs); } void scroll_down( int anzahl, int anf_zeile, int end_zeile) { /* Fenster runter rollen. */ union REGS intregs; intregs.x.ax = 0x700 + anzahl; /* Subfunktion AH = 7, */ /* AL = Anzahl Zeilen. */ intregs.x.cx = anf_zeile << 8; /* CH=anf_zeile, cl=0 */ intregs.x.dx = (end_zeile <<8) | 79; /* DH=end_zeile,DL=79 */ intregs.h.bh = 7; /* normales Attribut */ int86(VIDEO_INT, &intregs, &intregs); } void set_cur( int zeile, int spalte) /* versetzt den Cursor */ { /* der aktuellen Bildschirmseite.*/ union REGS intregs; intregs.h.ah = 2; intregs.h.dh = (BYTE)zeile; intregs.h.dl = (BYTE)spalte; intregs.h.bh = (BYTE)get_screen_page(); int86(VIDEO_INT, &intregs, &intregs); } void get_cur(int *zeile, int *spalte) /* holt die Cursor- */ { /* Position der aktuellen Bildschirmseite.*/ union REGS intregs; intregs.h.ah = 3; intregs.h.bh = (BYTE)get_screen_page(); int86(VIDEO_INT, &intregs, &intregs); *zeile = (unsigned)intregs.h.dh; *spalte = (unsigned)intregs.h.dl; } void cls(void) { scroll_up(0,0,24); /* Gesamten Bildschirm loeschen. */ set_cur(0,0); /* Cursor in Home-Position. */ } int get_screen_page(void) /* Aktuelle Bildschirmseite holen.*/ { union REGS intregs; intregs.h.ah = 15; /* Subfunktion AH = 15: */ /* Bildschirm-Modus feststellen. */ int86(VIDEO_INT, &intregs, &intregs); return (intregs.h.bh); } void set_screen_page(int seite) /* setzt die aktive Seite des */ { /* Bildschirmpuffers auf die */ /* angegebene Seite. */ union REGS intregs; intregs.x.ax = 0x500 + seite; /* Subfunktion AH = 5 */ int86(VIDEO_INT, &intregs, &intregs); } /* ------------------------------------------------------------- Ein kleines Testprogramm : */ /* #include <stdio.h> int main() { cls(); set_cur(23, 0); printf("Weiter mit <Return>\n"); set_cur(12, 20); printf("Ein Test!\n"); getchar(); scroll_up(3, 5, 20); getchar(); scroll_down(6, 5, 20); getchar(); set_screen_page(1); printf("\nAuf der 2. Seite !\n"); getchar(); set_screen_page(0); set_cur(0,0); printf("\nWieder auf der 1. Seite !\n"); getchar(); cls(); return 0; } */ /* Video.c --> Enthaelt die Funktionen * cls(), * scroll_up(), scroll_down(), * set_cur(), get_cur(), * set_screen_page(), get_screen_page() * * Die Prototypen dieser Funktionen befinden sich in BIO.H */ /* Hinweis: Es muss ein DOS-Compiler verwendet werden. * * (z.B. der GNU-Compiler fuer DOS auf der CD) */ #include <dos.h> #include "bio.h" #define VIDEO_INT 0x10 typedef unsigned char BYTE; void scroll_up( int anzahl, int anf_zeile, int end_zeile) { /* Fenster hoch rollen. */ union REGS intregs; intregs.x.ax = 0x600 + anzahl; /* Subfunktion AH = 6, */ /* AL = Anzahl Zeilen. */ intregs.x.cx = anf_zeile << 8; /* CH=anf_zeile, cl=0 */ intregs.x.dx = (end_zeile <<8) | 79; /* DH=end_zeile,DL=79 */ intregs.h.bh = 7; /* normales Attribut */ int86(VIDEO_INT, &intregs, &intregs); } void scroll_down( int anzahl, int anf_zeile, int end_zeile) { /* Fenster runter rollen. */ union REGS intregs; intregs.x.ax = 0x700 + anzahl; /* Subfunktion AH = 7, */ /* AL = Anzahl Zeilen. */ intregs.x.cx = anf_zeile << 8; /* CH=anf_zeile, cl=0 */ intregs.x.dx = (end_zeile <<8) | 79; /* DH=end_zeile,DL=79 */ intregs.h.bh = 7; /* normales Attribut */ int86(VIDEO_INT, &intregs, &intregs); } void set_cur( int zeile, int spalte) /* versetzt den Cursor */ { /* der aktuellen Bildschirmseite.*/ union REGS intregs; intregs.h.ah = 2; intregs.h.dh = (BYTE)zeile; intregs.h.dl = (BYTE)spalte; intregs.h.bh = (BYTE)get_screen_page(); int86(VIDEO_INT, &intregs, &intregs); } void get_cur(int *zeile, int *spalte) /* holt die Cursor- */ { /* Position der aktuellen Bildschirmseite.*/ union REGS intregs; intregs.h.ah = 3; intregs.h.bh = (BYTE)get_screen_page(); int86(VIDEO_INT, &intregs, &intregs); *zeile = (unsigned)intregs.h.dh; *spalte = (unsigned)intregs.h.dl; } void cls(void) { scroll_up(0,0,24); /* Gesamten Bildschirm loeschen. */ set_cur(0,0); /* Cursor in Home-Position. */ } int get_screen_page(void) /* Aktuelle Bildschirmseite holen.*/ { union REGS intregs; intregs.h.ah = 15; /* Subfunktion AH = 15: */ /* Bildschirm-Modus feststellen. */ int86(VIDEO_INT, &intregs, &intregs); return (intregs.h.bh); } void set_screen_page(int seite) /* setzt die aktive Seite des */ { /* Bildschirmpuffers auf die */ /* angegebene Seite. */ union REGS intregs; intregs.x.ax = 0x500 + seite; /* Subfunktion AH = 5 */ int86(VIDEO_INT, &intregs, &intregs); } /* ------------------------------------------------------------- Ein kleines Testprogramm : */ /* #include <stdio.h> int main() { cls(); set_cur(23, 0); printf("Weiter mit <Return>\n"); set_cur(12, 20); printf("Ein Test!\n"); getchar(); scroll_up(3, 5, 20); getchar(); scroll_down(6, 5, 20); getchar(); set_screen_page(1); printf("\nAuf der 2. Seite !\n"); getchar(); set_screen_page(0); set_cur(0,0); printf("\nWieder auf der 1. Seite !\n"); getchar(); cls(); return 0; } */ /* BIO.H --> Enthaelt die Prototypen der BIOS-Funktionen. */ /* --- Funktionen in VIDEO.C --- */ extern void scroll_up(int anzahl, int anf_zeile,int end_zeile); extern void scroll_down(int anzahl, int anf_zeile, int end_zeile); extern void set_cur(int zeile, int spalte); extern void get_cur(int *zeile, int *spalte); extern void cls(void); extern int get_screen_page(void); extern void set_screen_page(int page); /* --- Funktionen in GETCB.C / PUTCB.C --- */ extern int getcb(void); extern void putcb(int c); extern void putcb9(int c, unsigned count, unsigned modus); extern void balken(int zeile, int spalte, int laenge, int c, unsigned modus); extern int input(char *puffer, int max,... ); need your help, can't find my mistakes:((

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  • How to create a compiler in vb.net

    - by Cyclone
    Before answering this question, understand that I am not asking how to create my own programming language, I am asking how, using vb.net code, I can create a compiler for a language like vb.net itself. Essentially, the user inputs code, they get a .exe. By NO MEANS do I want to write my own language, as it seems other compiler related questions on here have asked. I also do not want to use the vb.net compiler itself, nor do I wish to duplicate the IDE. The exact purpose of what I wish to do is rather hard to explain, but all I need is a nudge in the right direction for writing a compiler (from scratch if possible) which can simply take input and create a .exe. I have opened .exe files as plain text before (my own programs) to see if I could derive some meaning from what I assumed would be human readable text, yet I was obviously sorely disappointed to see the random ascii, though it is understandable why this is all I found. I know that a .exe file is simply lines of code, being parsed by the computer it is on, but my question here really boils down to this: What code makes up a .exe? How could I go about making one in a plain text editor if I wanted to? (No, I do not want to do that, but if I understand the process my goals will be much easier to achieve.) What makes an executable file an executable file? Where does the logic of the code fit in? This is intended to be a programming question as opposed to a computer question, which is why I did not post it on SuperUser. I know plenty of information about the System.IO namespace, so I know how to create a file and write to it, I simply do not know what exactly I would be placing inside this file to get it to work as an executable file. I am sorry if this question is "confusing", "dumb", or "obvious", but I have not been able to find any information regarding the actual contents of an executable file anywhere. One of my google searches Something that looked promising EDIT: The second link here, while it looked good, was an utter fail. I am not going to waste hours of my time hitting keys and recording the results. "Use the "Alt" and the 3-digit combinations to create symbols that do not appear on the keyboard but that you need in the program." (step 4) How the heck do I know what symbols I need??? Thank you very much for your help, and my apologies if this question is a nooby or "bad" one. To sum this up simply: I want to create a program in vb.net that can compile code in a particular language to a single executable file. What methods exist that can allow me to do this, and if there are none, how can I go about writing my own from scratch?

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  • SocketChannel in Java sends data, but it doesn't get to destination application

    - by Peterson
    Hi Everybody, I'm suffering a lot to create a simple ChatServer in Java, using the NIO libraries. Wonder if someone could help me. I am doing that by using SocketChannel and Selector to handle multiple clients in a single thread. The problem is: I am able to accept new connections and get it's data, but when I try to send data back, the SocketChannel simply doesn't work. In the method write(), it returns a integer that is the same size of the data i'm passing to it, but the client never receives that data. Strangely, when I close the server application, the client receives the data. It's like the socketchannel maintains a buffer, and it only get flushed when I close the application. Here are some more details, to give you more information to help. I'm handling the events in this piece of code: private void run() throws IOException { ServerSocketChannel ssc = ServerSocketChannel.open(); // Set it to non-blocking, so we can use select ssc.configureBlocking( false ); // Get the Socket connected to this channel, and bind it // to the listening port this.serverSocket = ssc.socket(); InetSocketAddress isa = new InetSocketAddress( this.port ); serverSocket.bind( isa ); // Create a new Selector for selecting this.masterSelector = Selector.open(); // Register the ServerSocketChannel, so we can // listen for incoming connections ssc.register( masterSelector, SelectionKey.OP_ACCEPT ); while (true) { // See if we've had any activity -- either // an incoming connection, or incoming data on an // existing connection int num = masterSelector.select(); // If we don't have any activity, loop around and wait // again if (num == 0) { continue; } // Get the keys corresponding to the activity // that has been detected, and process them // one by one Set keys = masterSelector.selectedKeys(); Iterator it = keys.iterator(); while (it.hasNext()) { // Get a key representing one of bits of I/O // activity SelectionKey key = (SelectionKey)it.next(); // What kind of activity is it? if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) { // Aceita a conexão Socket s = serverSocket.accept(); System.out.println( "LOG: Conexao TCP aceita de " + s.getInetAddress() + ":" + s.getPort() ); // Make sure to make it non-blocking, so we can // use a selector on it. SocketChannel sc = s.getChannel(); sc.configureBlocking( false ); // Registra a conexao no seletor, apenas para leitura sc.register( masterSelector, SelectionKey.OP_READ ); } else if ( key.isReadable() ) { SocketChannel sc = null; // It's incoming data on a connection, so // process it sc = (SocketChannel)key.channel(); // Verifica se a conexão corresponde a um cliente já existente if((clientsMap.getClient(key)) != null){ boolean closedConnection = !processIncomingClientData(key); if(closedConnection){ int id = clientsMap.getClient(key); closeClient(id); } } else { boolean clientAccepted = processIncomingDataFromNewClient(key); if(!clientAccepted){ // Se o cliente não foi aceito, sua conexão é simplesmente fechada sc.socket().close(); sc.close(); key.cancel(); } } } } // We remove the selected keys, because we've dealt // with them. keys.clear(); } } This piece of code is simply handles new clients that wants to connect to the chat. So, a client makes a TCP connection to the server, and once it gets accepted, it sends data to the server following a simply text protocol, informing his id and asking to get registrated to the server. I handle this in the method processIncomingDataFromNewClient(key). I'm also keeping a map of clients and its connections in a data structure similar to a hashtable. I? doing that because I need to recover a client Id from a connection and a connection from a client Id. This is can be shown in: clientsMap.getClient(key). But the problem itself resides in the method processIncomingDataFromNewClient(key). There, I simply read the data that the client sent to me, validate it, and if it's ok, I send a message back to the client to tell that it is connected to the chat server. Here is a similar piece of code: private boolean processIncomingDataFromNewClient(SelectionKey key){ SocketChannel sc = (SocketChannel) key.channel(); String connectionOrigin = sc.socket().getInetAddress() + ":" + sc.socket().getPort(); int id = 0; //id of the client buf.clear(); int bytesRead = 0; try { bytesRead = sc.read(buf); if(bytesRead<=0){ System.out.println("Conexão fechada pelo: " + connectionOrigin); return false; } System.out.println("LOG: " + bytesRead + " bytes lidos de " + connectionOrigin); String msg = new String(buf.array(),0,bytesRead); // Do validations with the client sent me here // gets the client id }catch (Exception e) { e.printStackTrace(); System.out.println("LOG: Oops. Cliente não conhece o protocolo. Fechando a conexão: " + connectionOrigin); System.out.println("LOG: Primeiros 10 caracteres enviados pelo cliente: " + msg); return false; } } } catch (IOException e) { System.out.println("LOG: Erro ao ler dados da conexao: " + connectionOrigin); System.out.println("LOG: "+ e.getLocalizedMessage()); System.out.println("LOG: Fechando a conexão..."); return false; } // If it gets to here, the protocol is ok and we can add the client boolean inserted = clientsMap.addClient(key, id); if(!inserted){ System.out.println("LOG: Não foi possível adicionar o cliente. Ou ele já está conectado ou já têm clientes demais. Id: " + id); System.out.println("LOG: Fechando a conexão: " + connectionOrigin); return false; } System.out.println("LOG: Novo cliente conectado! Enviando mesnsagem de confirmação. Id: " + id + " Conexao: " + connectionOrigin); /* Here is the error */ sendMessage(id, "Servidor pet: connection accepted"); System.out.println("LOG: Novo cliente conectado! Id: " + id + " Conexao: " + connectionOrigin); return true; } And finally, the method sendMessage(SelectionKey key) looks like this: private void sendMessage(int destId, String msg) { Charset charset = Charset.forName("ISO-8859-1"); CharBuffer charBuffer = CharBuffer.wrap(msg, 0, msg.length()); ByteBuffer bf = charset.encode(charBuffer); //bf.flip(); int bytesSent = 0; SelectionKey key = clientsMap.getClient(destId); SocketChannel sc = (SocketChannel) key.channel(); try { / int total_bytes_sent = 0; while(total_bytes_sent < msg.length()){ bytesSent = sc.write(bf); total_bytes_sent += bytesSent; } System.out.println("LOG: Bytes enviados para o cliente " + destId + ": "+ total_bytes_sent + " Tamanho da mensagem: " + msg.length()); } catch (IOException e) { System.out.println("LOG: Erro ao mandar mensagem para: " + destId); System.out.println("LOG: " + e.getLocalizedMessage()); } } So, what is happening is that the server, when send a message, prints something like this: LOG: Bytes sent to the client: 28 Size of the message: 28 So, it tells that it sent the data, but the chat client keeps blocking, waiting in the recv() method. So, the data never gets to it. When I close the server application, though, all the data appears in the client. I wonder why. It is important to say that the client is in C and the server JAVA, and I'm running both in the same machine, an Ubuntu Guest in virtualbox under windows. I also run both under windows host and under linuxes hosts, and keep getting the same strange problem. I'm sorry for the great lenght of this question, but I already searched a lot of places for an answer, found a lot of tutorials and questions, including here at StackOverflow, but coundn't find a reasonable explanation. I am really not liking this Java NIO, and i saw a lot of people complaining about it too. I am thinking that if I had done that in C it would have been a lot easier :-D So, if someone could help me and even discuss this behavor, it would be great! :-) Thanks everybody in advance, Péterson

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  • Matching unmatched strings based on a unknown pattern

    - by Polity
    Alright guys, i really hurt my brain over this one and i'm curious if you guys can give me any pointers towards the right direction i should be taking. The situation is this: Lets say, i have a collection of strings (let it be clear that the pattern of this strings is unknown. For a fact, i can say that the string contain only signs from the ASCII table and therefore, i dont have to worry about weird Chinese signs). For this example, i take the following collection of strings (note that the strings dont have to make any human sence so dont try figguring them out :)): "[001].[FOO].[TEST] - 'foofoo.test'", "[002].[FOO].[TEST] - 'foofoo.test'", "[003].[FOO].[TEST] - 'foofoo.test'", "[001].[FOO].[TEST] - 'foofoo.test.sample'", "[002].[FOO].[TEST] - 'foofoo.test.sample'", "-001- BAR.[TEST] - 'bartest.xx1", "-002- BAR.[TEST] - 'bartest.xx1" Now, what i need to have is a way of finding logical groups (and subgroups) of these set of strings, so in the above example, just by rational thinking, you can combine the first 3, the 2 after that and the last 2. Also the resulting groups from the first 5 can be combined in one main group with 2 subgroups, this should give you something like this: { { "[001].[FOO].[TEST] - 'foofoo.test'", "[002].[FOO].[TEST] - 'foofoo.test'", "[003].[FOO].[TEST] - 'foofoo.test'", } { "[001].[FOO].[TEST] - 'foofoo.test.sample'", "[002].[FOO].[TEST] - 'foofoo.test.sample'", } { "-001- BAR.[TEST] - 'bartest.xx1", "-002- BAR.[TEST] - 'bartest.xx1" } } Sorry for the layout above but indenting with 4 spaces doesnt seem to work correctly (or im frakk'n it up). Anyways, I'm not sure how to approach this problem (how to get the result desired as indicated above). First of, i thought of creating a huge set of regexes which would parse most known patterns but the amount of different patterns is just to huge that this isn't realistic. Another think i thought of was parsing each indidual word within a string (so strip all non alphabetic or numeric characters and split by those), and if X% matches, i can assume the strings belong to the same group. (where X wil probably be around 80/90). However, i find the area of speculation kinda big. For example, when matching strings with each 20 words, the change of hitting above 80% is kinda big (that means that 4 words can differ), however when matching only 8 words, 2 words at most can differ. My question to you is, what would be a logical approach in the above situation? Thanks in advance!

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  • Using NHibernate to map a nChar column to an enumerated type

    - by Morrislgn
    Hello Folks, I am trying to map a table frp, a SQL Server 2005 DB to a class which contains an enum: public class MyClass{ private YesNoOptional addressSetting; public YesNoOptional AddressSetting{ {get; set;} } } public enum YesNoOptional { Yes, No, Optional } This will dictate that one of three values is inserted into the corresponding column - 'Y', 'N', 'O'. This column is of type nchar(1). My mapping file is like so (addressSetting is the property which is causing the problem): <class name="IncidentDefinition" table="IR_INCIDENT_DEF" lazy="false" > <id name="Guid" column="INT_GUID" > <generator class="guid"></generator> </id> <property name="Reference" column="INT_REF" ></property> <property name="Description" column="INT_DESCRIPTION" ></property> <property name="AddressSetting" column="INT_ADDRESS_REQ" ></property> <property name="Active" column="INT_ACTIVE" type="YesNo"></property> <property name="PinDocId" column="INT_PIN_DOC_ID"></property> </class> Using the config above I get the following error: NHibernate.ADOException: could not initialize a collection: System.FormatException: Input string was not in a correct format.. If I try to map the enum using a custom type like so: <property name="AddressSetting" column="INT_ADDRESS_REQ" type="ML.Types.YesNoOptional, ML.Types" ></property> Error: System.FormatException: Input string was not in a correct format. Next, if I try using a specific type like so: <property name="AddressSetting" column="INT_ADDRESS_REQ" type="String" ></property> This error is generated: NHibernate.PropertyAccessException: The type System.String can not be assigned to a property of type System.ArgumentException: Object of type 'System.String' cannot be converted to type 'ML.Types.YesNoOptional'.. As a last resort I tried to specify the type as a char like so: <property name="AddressSetting" column="INT_ADDRESS_REQ" type="Char" ></property> This works a bit better, as it in it doesnt throw an error, however instead of returning the character from the table and mapping it to the enumerated type the ASCII value of the character is returned instead - so Y is represented by 89! I am hoping someone can explain what I am doing wrong and\or how why this is happening please? Thanks Morris

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  • ASP.NET Web Service - how to handle special characters in strings?

    - by Vlorg
    To show this fundamental issue in .NET and the reason for this question, I have written a simple test web service with one method (EditString), and a consumer console app that calls it. They are both standard web service/console applications created via File/New Project, etc., so I won't list the whole code - just the methods in question: Web method: [WebMethod] public string EditString(string s, bool useSpecial) { return s + (useSpecial ? ((char)19).ToString() : ""); } [You can see it simply returns the string s if useSpecial is false. If useSpecial is true, it returns s + char 19.] Console app: TestService.Service1 service = new SCTestConsumer.TestService.Service1(); string response1 = service.EditString("hello", false); Console.WriteLine(response1); string response2 = service.EditString("hello", true); // fails! Console.WriteLine(response2); [The second response fails, because the method returns hello + a special character (ascii code 19 for argument's sake).] The error is: There is an error in XML document (1, 287) Inner exception: "'', hexadecimal value 0x13, is an invalid character. Line 1, position 287." A few points worth mentioning: The web method itself WORKS FINE when browsing directly to the ASMX file (e.g. http://localhost:2065/service1.asmx), and running the method through this (with the same parameters as in the console application) - i.e. displays XML with the string hello + char 19. Checking the serialized XML in other ways shows the special character is being encoded properly (the SERVER SIDE seems to be ok which is GOOD) So it seems the CLIENT SIDE has the issue - i.e. the .NET generated proxy class code doesn't handle special characters This is part of a bigger project where objects are passed in and out of the web methods - that contain string attributes - these are what need to work properly. i.e. we're de/serializing classes. Any suggestions for a workaround and how to implement it? Or have I completely missed something really obvious!!? Thanks in advance... PS. I've not had much luck with getting it to use CDATA tags (does .NET support these out of the box?).

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  • Calculations in a table of data

    - by Christian W
    I have a table of data with survey results, and I want to do certain calculations on this data. The datastructure is somewhat like this: ____________________________________________________________________________________ | group |individual | key | key | key | | | |subkey|subkey|subkey|subkey|subkey|subkey|subkey|subkey|subkey| | | |q|q|q |q |q |q|q|q |q|q|q |q |q |q|q|q |q|q|q |q |q |q|q|q | |-------|-----------|-|-|--|--|---|-|-|--|-|-|--|--|---|-|-|--|-|-|--|--|---|-|-|--| | 1 | 0001 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 1 | 0002 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 1 | 0003 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 2 | 0004 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 2 | 0005 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 3 | 0006 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 4 | 0007 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | ------------------------------------------------------------------------------------ Excuse my poor ascii skills... So, every individual belongs to a group, and has answered some questions. These questions are always grouped in keys and subkeys. Is there any simple method to calculate averages, deviations and similar based on the groupings. Something like public float getAverage(int key, int individual); float avg = getAverage(5,7); I think what I'm asking is what would be the best way to structure the data in C# to make it as easy as possible to work with? I have started making classes for every entity, but I got confused somewhere and something stopped working. So before I continue along this path, I was wondering if there are any other, better, ways of doing this? (Every individual can also have describing variables, like agegroup and such, but that's not important for the base functionality.) Our current solution does all calculations inline in the queries when requesting the data from the database. This works, but it's slow and the number of queries equals questions * individuals + keys * individuals, which could be alot if individual queries. Any suggestions?

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  • .NET C# Filestream writing to file and reading the bfile

    - by pythonrg7
    I have a web service that checks a dictionary to see if a file exists and then if it does exist it reads the file, otherwise it saves to the file. This is from a web app. I wonder what is the best way to do this because I occasionally get a FileNotFoundException exception if the same file is accessed at the same time. Here's the relevant parts of the code: String signature; signature = "FILE," + value1 + "," + value2 + "," + value3 + "," + value4; // this is going to be the filename string result; MultipleRecordset mrSummary = new MultipleRecordset(); // MultipleRecordset is an object that retrieves data from a sql server database if (mrSummary.existsFile(signature)) { result = mrSummary.retrieveFile(signature); } else { result = mrSummary.getMultipleRecordsets(System.Configuration.ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString.ToString(), value1, value2, value3, value4); mrSummary.saveFile(signature, result); } Here's the code to see if the file already exists: private static Dictionary dict = new Dictionary(); public bool existsFile(string signature) { if (dict.ContainsKey(signature)) { return true; } else { return false; } } Here's what I use to retrieve if it already exists: try { byte[] buffer; FileStream fileStream = new FileStream(@System.Configuration.ConfigurationManager.AppSettings["CACHEPATH"] + filename, FileMode.Open, FileAccess.Read, FileShare.Read); try { int length = 0x8000; // get file length buffer = new byte[length]; // create buffer int count; // actual number of bytes read JSONstring = ""; while ((count = fileStream.Read(buffer, 0, length)) > 0) { JSONstring += System.Text.ASCIIEncoding.ASCII.GetString(buffer, 0, count); } } finally { fileStream.Close(); } } catch (Exception e) { JSONstring = "{\"error\":\"" + e.ToString() + "\"}"; } If the file doesn't previously exist it saves the JSON to the file: try { if (dict.ContainsKey(filename) == false) { dict.Add(filename, true); } else { this.retrieveFile(filename, ipaddress); } } catch { } try { TextWriter tw = new StreamWriter(@System.Configuration.ConfigurationManager.AppSettings["CACHEPATH"] + filename); tw.WriteLine(JSONstring); tw.Close(); } catch { } Here are the details to the exception I sometimes get from running the above code: System.IO.FileNotFoundException: Could not find file 'E:\inetpub\wwwroot\cache\FILE,36,36.25,14.5,14.75'. File name: 'E:\inetpub\wwwroot\cache\FILE,36,36.25,14.5,14.75' at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy) at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share) at com.myname.business.MultipleRecordset.retrieveFile(String filename, String ipaddress)

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  • Interop.Outlook.UserProperties.Add causing problem during connection time

    - by Akie
    Hi All, I have created a plug-in for outlook. Plug-in has only below code. private void OnNewOutlookInspector(Outlook.Inspector OutlookInsptr) { Outlook.MailItem MlItem = (Outlook.MailItem)OutlookInsptr.CurrentItem; //if I remove below line. Everything is working fine. MlItem.UserProperties.Add("INSPINIT", Outlook.OlUserPropertyType.olText , true , true ).Value = "1"; } public void OnConnection(object application, Extensibility.ext_ConnectMode connectMode, object addInInst, ref System.Array custom) { applicationObject = application; addInInstance = addInInst; MessageBox.Show("in connection new 2"); OutlkApp = (Outlook.Application)application; OutlkInsptrs = OutlkApp.Inspectors; OutlkInsptrs.NewInspector += new Outlook.InspectorsEvents_NewInspectorEventHandler(OnNewOutlookInspector); } Problem I am facing is, When I send HTML mail while plug-in is enabled, receiving end it is being received as a plain text. Below is the mail content along with the header and body at recieving end. x-sender: [email protected] x-receiver: [email protected] Received: from blr-s-07.pointcrossblr.com ([192.168.1.107]) by blr-ws-134.pointcrossblr.com with Microsoft SMTPSVC(6.0.2600.5949); Wed, 22 Dec 2010 17:11:02 +0530 Received: from blrws134 ([192.168.1.175]) by blr-s-07.pointcrossblr.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 22 Dec 2010 17:11:02 +0530 From: "Ashif Nataliya" <[email protected]> To: <[email protected]> Cc: <[email protected]> Subject: RTF FRM blr to pc.com cc blr-ws-134 Date: Wed, 22 Dec 2010 17:11:02 +0530 Message-ID: <[email protected]> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_NextPart_000_00F7_01CBA1FB.36115580" X-Mailer: Microsoft Outlook 14.0 Content-Language: en-us X-MS-TNEF-Correlator: 00000000DCB2344DE8F50F4FBC91085BB5C06D55A4172000 thread-index: AcuhzRuTOBkvHPUnS1aLi9+cHNAWhA== Return-Path: [email protected] X-OriginalArrivalTime: 22 Dec 2010 11:41:02.0822 (UTC) FILETIME=[1C788860:01CBA1CD] This is a multipart message in MIME format. ------=_NextPart_000_00F7_01CBA1FB.36115580 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit HTML Test Test Mail ------=_NextPart_000_00F7_01CBA1FB.36115580 Content-Type: application/ms-tnef; name="winmail.dat" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="winmail.dat" // and some other code..... Any help is appreciated. Thanks.

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  • Will these optimizations to my Ruby implementation of diff improve performance in a Rails app?

    - by grg-n-sox
    <tl;dr> In source version control diff patch generation, would it be worth it to use the optimizations listed at the very bottom of this writing (see <optimizations>) in my Ruby implementation of diff for making diff patches? </tl;dr> <introduction> I am programming something I have never done before and there might already be tools out there to do the exact thing I am programming but at this point I am having too much fun to care so I am still going to do it from scratch, even if there is a tool for this. So anyways, I am working on a Ruby on Rails app and need a certain feature. Basically I want each entry in a table of mine, let's say for example a table of video games, to have a stored chunk of text that represents a review or something of the sort for that table entry. However, I want this text to be both editable by any registered user and also keep track of different submissions in a version control system. The simplest solution I could think of is just implement a solution that keeps track of the text body and the diff patch history of different versions of the text body as objects in Ruby and then serialize it, preferably in human readable form (so I'll most likely use YAML for this) for editing if needed due to corruption by a software bug or a mistake is made by an admin doing some version editing. So at first I just tried to dive in head first into this feature to find that the problem of generating a diff patch is more difficult that I thought to do efficiently. So I did some research and came across some ideas. Some I have implemented already and some I have not. However, it all pretty much revolves around the longest common subsequence problem, as you would already know if you have already done anything with diff or diff-like features, and optimization the function that solves it. Currently I have it so it truncates the compared versions of the text body from the beginning and end until non-matching lines are found. Then it solves the problem using a comparison matrix, but instead of incrementing the value stored in a cell when it finds a matching line like in most longest common subsequence algorithms I have seen examples of, I increment when I have a non-matching line so as to calculate edit distance instead of longest common subsequence. Although as far as I can tell between the two approaches, they are essentially two sides of the same coin so either could be used to derive an answer. It then back-traces through the comparison matrix and notes when there was an incrementation and in which adjacent cell (West, Northwest, or North) to determine that line's diff entry and assumes all other lines to be unchanged. Normally I would leave it at that, but since this is going into a Rails environment and not just some stand-alone Ruby script, I started getting worried about needing to optimize at least enough so if a spammer that somehow knew how I implemented the version control system and knew my worst case scenario entry still wouldn't be able to hit the server that bad. After some searching and reading of research papers and articles through the internet, I've come across several that seem decent but all seem to have pros and cons and I am having a hard time deciding how well in this situation that the pros and cons balance out. So are the ones listed here worth it? I have listed them with known pros and cons. </introduction> <optimizations> Chop the compared sequences into multiple chucks of subsequences by splitting where lines are unchanged, and then truncating each section of unchanged lines at the beginning and end of each section. Then solve the edit distance of each subsequence. Pro: Changes the time increase as the changed area gets bigger from a quadratic increase to something more similar to a linear increase. Con: Figuring out where to split already seems like you have to solve edit distance except now you don't care how it is changed. Would be fine if this was solvable by a process closer to solving hamming distance but a single insertion would throw this off. Use a cryptographic hash function to both convert all sequence elements into integers and ensure uniqueness. Then solve the edit distance comparing the hash integers instead of the sequence elements themselves. Pro: The operation of comparing two integers is faster than the operation of comparing two strings, so a slight performance gain is received after every comparison, which can be a lot overall. Con: Using a cryptographic hash function takes time to convert all the sequence elements and may end up costing more time to do the conversion that you gain back from the integer comparisons. You could use the built in hash function for a string but that will not guarantee uniqueness. Use lazy evaluation to only calculate the three center-most diagonals of the comparison matrix and then only calculate additional diagonals as needed. And then also use this approach to possibly remove the need on some comparisons to compare all three adjacent cells as desribed here. Pro: Can turn an algorithm that always takes O(n * m) time and make it so only worst case scenario is that time, best case becomes practically linear, and average case is somewhere between the two. Con: It is an algorithm I've only seen implemented in functional programming languages and I am having a difficult time comprehending how to convert this into Ruby based on how it is described at the site linked to above. Make a C module and do the hard work at the native level in C and just make a Ruby wrapper for it so Ruby can make all the calls to it that it needs. Pro: I have to imagine that evaluating something like this in could be a LOT faster. Con: I have no idea how Rails handles apps with ruby code that has C extensions and it hurts the portability of the app. This is an optimization for after the solving of edit distance, but idea is to store additional combined diffs with the ones produced by each version to make a delta-tree data structure with the most recently made diff as the root node of the tree so getting to any version takes worst case time of O(log n) instead of O(n). Pro: Would make going back to an old version a lot faster. Con: It would mean every new commit, the delta-tree would get a new root node that will cost time to reorganize the delta-tree for an operation that will be carried out a lot more often than going back a version, not to mention the unlikelihood it will be an old version. </optimizations> So are these things worth the effort?

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  • Read variable-length records from a buffer - weird memory issues

    - by bsg
    Hi, I'm trying to implement an i/o intensive quicksort (C++ qsort) on a very large dataset. In the interests of speed, I'd like to read in a chunk of data at a time into a buffer and then use qsort to sort it inside the buffer. (I am currently working with text files but would like to move to binary soon.) However, my data is composed of variable-length records, and qsort needs to be told the length of the record in order to sort. Is there any way to standardize this? The only thing I could think of was rather convoluted: my program currently reads from the buffer until it hits a linefeed character ('10' in ascii), transferring each character over to another array. When it finds a linefeed (the delimiter in the input file), it fills the number of spaces remaining in the buffer for that record (record size is set to 30) with null characters. This way, I should end up with a buffer full of fixed-size records to give qsort. I know there are several problems with my approach, one being that it's just clumsy, another that the record size might conceivably be larger than 30, but is generally much less. Is there a better way of doing this? As well, my current code doesn't even work. When I debug it, it seems to be transferring characters from one buffer to the other, but when I try to print out the buffer, it contains only the first record. Here is my code: FILE *fp; unsigned char *buff; unsigned char *realbuff; FILE *inputFiles[NUM_INPUT_FILES]; buff = (unsigned char *) malloc(2048); realbuff = (unsigned char *) malloc(NUM_RECORDS * RECORD_SIZE); fp = fopen("postings0.txt", "r"); if(fp) { fread(buff, 1, 2048, fp); /*for(int i=0; i <30; i++) cout << buff[i] <<endl;*/ int y=0; int recordcounter = 0; //cout << buff; for(int i=0;i <100; i++) { if(buff[i] != char(10)) { realbuff[y] = buff[i]; y++; recordcounter++; } else { if(recordcounter < RECORD_SIZE) for(int j=recordcounter; j < RECORD_SIZE;j++) { realbuff[y] = char(0); y++; } recordcounter = 0; } } cout << realbuff <<endl; cout << buff; } else cout << "sorry"; Thank you very much, bsg

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  • Adapting a HTML/CSS dropdown menu to multi-level

    - by Adam Nygate
    Ive been trying to make the original dropdown into multi level for a site im working on. All of my attempts have failed (. For some reason i can only do "margin-right" to align the elements, and this causes some problems. I think it has something to do with the position attribute. Here is my HTML: <ol id="nav"> <li><a href="index.php">Home</a></li> <li class="dropdown_alignedLeft"> <a href="">Products</a> <ul><li class="dropdown_alignedRight"> <a href="">iPoP</a> <ul style="margin-right:-400px; top:0px;-webkit-border-top-right-radius: 5px;border-top-right-radius: 5px;-moz-border-radius-topright: 5px;"><li><a href="customers.php?category=ipop">iPoP - Network Solutions for Vessels</a></li></ul><li class="dropdown_alignedRight"> <a href="">Cameras</a> <ul style="margin-right:-400px; top:0px;-webkit-border-top-right-radius: 5px;border-top-right-radius: 5px;-moz-border-radius-topright: 5px;"><li><a href="customers.php?category=icam">iCam 501 Ultra - Intrinsically Safe Digital Camera with Flash</a></li></ul><li class="dropdown_alignedRight"> <a href="">BNWAS</a> <ul style="margin-right:-400px; top:0px;-webkit-border-top-right-radius: 5px;border-top-right-radius: 5px;-moz-border-radius-topright: 5px;"><li><a href="customers.php?category=bnwas">BNWAS - Bridge Navigation Watch Alarm System</a></li></ul><li class="dropdown_alignedRight"> <a href="">Lighting</a> <ul style="margin-right:-400px; top:0px;-webkit-border-top-right-radius: 5px;border-top-right-radius: 5px;-moz-border-radius-topright: 5px;"><li><a href="customers.php?category=peli">Peli 2690 - Intrinsically Safe LED Head Lamp</a></li></ul><li class="dropdown_alignedRight"> <a href="">Communication</a> <ul style="margin-right:-400px; top:0px;-webkit-border-top-right-radius: 5px;border-top-right-radius: 5px;-moz-border-radius-topright: 5px;"><li><a href="customers.php?category=handy">Ex-Handy 06 - Intrinsically Safe Cell Phone</a></li></ul> </ul> <li class="dropdown_alignedLeft"> <a href="">Customers</a> <ul> <li><a href="customers.php?category=maritime">Maritime</a></li> <li><a href="customers.php?category=non">Non-Maritime</a></li> <li class="dropdown_lastItem"><a href="customers.php?category=organizations">Regulatory Organizations</a></li> </ul> <li><a href="order.php">Product Enquiry</a></li> <li><a href="contact.php">Contact Us</a></li> <li class="dropdown_alignedLeft"> <a href="">Company</a> <ul> <!-- <li><a href="">About Us</a></li> --> <li><a href="newsandpr.php?category=News">News</a></li> <li class="dropdown_lastItem"><a href="newsandpr.php?category=Press Release">Press Releases</a></li> </ul> </ol> And my CSS: #nav { float:right; margin:15px 0 0; } #nav li { float:left; } #nav li a { display:block; font-family:"PT Sans","Helvetica Neue",Arial,sans-serif; font-size:16px; text-decoration:none; color:#2B95C8; padding:10px 20px 20px; } .dropdown_alignedLeft,.dropdown_alignedRight { position:relative; } #nav .dropdown_alignedLeft>a,#nav .dropdown_alignedRight>a { background:url(../images/dropdown_arrow_blue.png) no-repeat top right; padding:10px 30px 20px 20px; } #nav .dropdown_alignedLeft:hover>a,#nav .dropdown_alignedRight:hover>a { -moz-border-radius-topleft:5px; -moz-border-radius-topright:5px; -moz-border-radius-bottomright:0; -moz-border-radius-bottomleft:0; -webkit-border-top-left-radius:5px; -webkit-border-top-right-radius:5px; -webkit-border-bottom-right-radius:0; -webkit-border-bottom-left-radius:0; border-top-left-radius:5px; border-top-right-radius:5px; border-bottom-right-radius:0; border-bottom-left-radius:0; color:#FFF; background:#2378A1 url(../images/dropdown_arrow_blue.png) no-repeat bottom right; } .dropdown_alignedLeft ul,.dropdown_alignedRight ul { display:none; } #nav .dropdown_alignedLeft:hover>ul,#nav .dropdown_alignedRight:hover>ul { display:block; z-index:100; position:absolute; top:50px; -moz-border-radius-topleft:0; -moz-border-radius-topright:0; -moz-border-radius-bottomright:5px; -moz-border-radius-bottomleft:5px; -webkit-border-top-left-radius:0; -webkit-border-top-right-radius:0; -webkit-border-bottom-right-radius:5px; -webkit-border-bottom-left-radius:5px; border-top-left-radius:0; border-top-right-radius:0; border-bottom-right-radius:5px; border-bottom-left-radius:5px; background:#2378A1; padding:0 0 6px; } #nav .dropdown_alignedRight:hover>ul { top:50px; right:0; text-align:right; } #nav li ul li { float:none; border-bottom:1px dashed #2B95C8; margin:0 20px; } #nav li ul li.dropdown_innerTitle { border:none; font-family:"Helvetica Neue",Arial,sans-serif; font-size:15px; white-space:nowrap; color:#C8DDE7; margin:10px 20px 0; padding:10px 0; } #nav li ul li.dropdown_lastItem { border:none; } #nav li ul li a { font-family:"Helvetica Neue",Arial,sans-serif; font-size:13px; color:#FFF; white-space:nowrap; padding:10px 0 9px; } #nav>li:hover>a,#nav li .current_page { color:#2378A1; background:url(../images/current_page_arrow_blue.png) no-repeat center bottom; } #nav li ul li a:hover { color: #C8DDE7; } For a live version of the menu, please go here: JSFiddle - Live Menu

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  • c# interop with ghostscript

    - by yodaj007
    I'm trying to access some Ghostscript functions like so: [DllImport(@"C:\Program Files\GPLGS\gsdll32.dll", EntryPoint = "gsapi_revision")] public static extern int Foo(gsapi_revision_t x, int len); public struct gsapi_revision_t { [MarshalAs(UnmanagedType.LPTStr)] string product; [MarshalAs(UnmanagedType.LPTStr)] string copyright; long revision; long revisiondate; } public static void Main() { gsapi_revision_t foo = new gsapi_revision_t(); Foo(foo, Marshal.SizeOf(foo)); This corresponds with these definitions from the iapi.h header from ghostscript: typedef struct gsapi_revision_s { const char *product; const char *copyright; long revision; long revisiondate; } gsapi_revision_t; GSDLLEXPORT int GSDLLAPI gsapi_revision(gsapi_revision_t *pr, int len); But my code is reading nothing into the string fields. If I add 'ref' to the function, it reads gibberish. However, the following code reads in the data just fine: public struct gsapi_revision_t { IntPtr product; IntPtr copyright; long revision; long revisiondate; } public static void Main() { gsapi_revision_t foo = new gsapi_revision_t(); IntPtr x = Marshal.AllocHGlobal(20); for (int i = 0; i < 20; i++) Marshal.WriteInt32(x, i, 0); int result = Foo(x, 20); IntPtr productNamePtr = Marshal.ReadIntPtr(x); IntPtr copyrightPtr = Marshal.ReadIntPtr(x, 4); long revision = Marshal.ReadInt64(x, 8); long revisionDate = Marshal.ReadInt64(x, 12); byte[] dest = new byte[1000]; Marshal.Copy(productNamePtr, dest, 0, 1000); string name = Read(productNamePtr); string copyright = Read(copyrightPtr); } public static string Read(IntPtr p) { List<byte> bits = new List<byte>(); int i = 0; while (true) { byte b = Marshal.ReadByte(new IntPtr(p.ToInt64() + i)); if (b == 0) break; bits.Add(b); i++; } return Encoding.ASCII.GetString(bits.ToArray()); } So what am I doing wrong with marshaling?

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  • Steganography Experiment - Trouble hiding message bits in DCT coefficients

    - by JohnHankinson
    I have an application requiring me to be able to embed loss-less data into an image. As such I've been experimenting with steganography, specifically via modification of DCT coefficients as the method I select, apart from being loss-less must also be relatively resilient against format conversion, scaling/DSP etc. From the research I've done thus far this method seems to be the best candidate. I've seen a number of papers on the subject which all seem to neglect specific details (some neglect to mention modification of 0 coefficients, or modification of AC coefficient etc). After combining the findings and making a few modifications of my own which include: 1) Using a more quantized version of the DCT matrix to ensure we only modify coefficients that would still be present should the image be JPEG'ed further or processed (I'm using this in place of simply following a zig-zag pattern). 2) I'm modifying bit 4 instead of the LSB and then based on what the original bit value was adjusting the lower bits to minimize the difference. 3) I'm only modifying the blue channel as it should be the least visible. This process must modify the actual image and not the DCT values stored in file (like jsteg) as there is no guarantee the file will be a JPEG, it may also be opened and re-saved at a later stage in a different format. For added robustness I've included the message multiple times and use the bits that occur most often, I had considered using a QR code as the message data or simply applying the reed-solomon error correction, but for this simple application and given that the "message" in question is usually going to be between 10-32 bytes I have plenty of room to repeat it which should provide sufficient redundancy to recover the true bits. No matter what I do I don't seem to be able to recover the bits at the decode stage. I've tried including / excluding various checks (even if it degrades image quality for the time being). I've tried using fixed point vs. double arithmetic, moving the bit to encode, I suspect that the message bits are being lost during the IDCT back to image. Any thoughts or suggestions on how to get this working would be hugely appreciated. (PS I am aware that the actual DCT/IDCT could be optimized from it's naive On4 operation using row column algorithm, or an FDCT like AAN, but for now it just needs to work :) ) Reference Papers: http://www.lokminglui.com/dct.pdf http://arxiv.org/ftp/arxiv/papers/1006/1006.1186.pdf Code for the Encode/Decode process in C# below: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Drawing.Imaging; using System.Drawing; namespace ImageKey { public class Encoder { public const int HIDE_BIT_POS = 3; // use bit position 4 (1 << 3). public const int HIDE_COUNT = 16; // Number of times to repeat the message to avoid error. // JPEG Standard Quantization Matrix. // (to get higher quality multiply by (100-quality)/50 .. // for lower than 50 multiply by 50/quality. Then round to integers and clip to ensure only positive integers. public static double[] Q = {16,11,10,16,24,40,51,61, 12,12,14,19,26,58,60,55, 14,13,16,24,40,57,69,56, 14,17,22,29,51,87,80,62, 18,22,37,56,68,109,103,77, 24,35,55,64,81,104,113,92, 49,64,78,87,103,121,120,101, 72,92,95,98,112,100,103,99}; // Maximum qauality quantization matrix (if all 1's doesn't modify coefficients at all). public static double[] Q2 = {1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1}; public static Bitmap Encode(Bitmap b, string key) { Bitmap response = new Bitmap(b.Width, b.Height, PixelFormat.Format32bppArgb); uint imgWidth = ((uint)b.Width) & ~((uint)7); // Maximum usable X resolution (divisible by 8). uint imgHeight = ((uint)b.Height) & ~((uint)7); // Maximum usable Y resolution (divisible by 8). // Start be transferring the unmodified image portions. // As we'll be using slightly less width/height for the encoding process we'll need the edges to be populated. for (int y = 0; y < b.Height; y++) for (int x = 0; x < b.Width; x++) { if( (x >= imgWidth && x < b.Width) || (y>=imgHeight && y < b.Height)) response.SetPixel(x, y, b.GetPixel(x, y)); } // Setup the counters and byte data for the message to encode. StringBuilder sb = new StringBuilder(); for(int i=0;i<HIDE_COUNT;i++) sb.Append(key); byte[] codeBytes = System.Text.Encoding.ASCII.GetBytes(sb.ToString()); int bitofs = 0; // Current bit position we've encoded too. int totalBits = (codeBytes.Length * 8); // Total number of bits to encode. for (int y = 0; y < imgHeight; y += 8) { for (int x = 0; x < imgWidth; x += 8) { int[] redData = GetRedChannelData(b, x, y); int[] greenData = GetGreenChannelData(b, x, y); int[] blueData = GetBlueChannelData(b, x, y); int[] newRedData; int[] newGreenData; int[] newBlueData; if (bitofs < totalBits) { double[] redDCT = DCT(ref redData); double[] greenDCT = DCT(ref greenData); double[] blueDCT = DCT(ref blueData); int[] redDCTI = Quantize(ref redDCT, ref Q2); int[] greenDCTI = Quantize(ref greenDCT, ref Q2); int[] blueDCTI = Quantize(ref blueDCT, ref Q2); int[] blueDCTC = Quantize(ref blueDCT, ref Q); HideBits(ref blueDCTI, ref blueDCTC, ref bitofs, ref totalBits, ref codeBytes); double[] redDCT2 = DeQuantize(ref redDCTI, ref Q2); double[] greenDCT2 = DeQuantize(ref greenDCTI, ref Q2); double[] blueDCT2 = DeQuantize(ref blueDCTI, ref Q2); newRedData = IDCT(ref redDCT2); newGreenData = IDCT(ref greenDCT2); newBlueData = IDCT(ref blueDCT2); } else { newRedData = redData; newGreenData = greenData; newBlueData = blueData; } MapToRGBRange(ref newRedData); MapToRGBRange(ref newGreenData); MapToRGBRange(ref newBlueData); for(int dy=0;dy<8;dy++) { for(int dx=0;dx<8;dx++) { int col = (0xff<<24) + (newRedData[dx+(dy*8)]<<16) + (newGreenData[dx+(dy*8)]<<8) + (newBlueData[dx+(dy*8)]); response.SetPixel(x+dx,y+dy,Color.FromArgb(col)); } } } } if (bitofs < totalBits) throw new Exception("Failed to encode data - insufficient cover image coefficients"); return (response); } public static void HideBits(ref int[] DCTMatrix, ref int[] CMatrix, ref int bitofs, ref int totalBits, ref byte[] codeBytes) { int tempValue = 0; for (int u = 0; u < 8; u++) { for (int v = 0; v < 8; v++) { if ( (u != 0 || v != 0) && CMatrix[v+(u*8)] != 0 && DCTMatrix[v+(u*8)] != 0) { if (bitofs < totalBits) { tempValue = DCTMatrix[v + (u * 8)]; int bytePos = (bitofs) >> 3; int bitPos = (bitofs) % 8; byte mask = (byte)(1 << bitPos); byte value = (byte)((codeBytes[bytePos] & mask) >> bitPos); // 0 or 1. if (value == 0) { int a = DCTMatrix[v + (u * 8)] & (1 << HIDE_BIT_POS); if (a != 0) DCTMatrix[v + (u * 8)] |= (1 << HIDE_BIT_POS) - 1; DCTMatrix[v + (u * 8)] &= ~(1 << HIDE_BIT_POS); } else if (value == 1) { int a = DCTMatrix[v + (u * 8)] & (1 << HIDE_BIT_POS); if (a == 0) DCTMatrix[v + (u * 8)] &= ~((1 << HIDE_BIT_POS) - 1); DCTMatrix[v + (u * 8)] |= (1 << HIDE_BIT_POS); } if (DCTMatrix[v + (u * 8)] != 0) bitofs++; else DCTMatrix[v + (u * 8)] = tempValue; } } } } } public static void MapToRGBRange(ref int[] data) { for(int i=0;i<data.Length;i++) { data[i] += 128; if(data[i] < 0) data[i] = 0; else if(data[i] > 255) data[i] = 255; } } public static int[] GetRedChannelData(Bitmap b, int sx, int sy) { int[] data = new int[8 * 8]; for (int y = sy; y < (sy + 8); y++) { for (int x = sx; x < (sx + 8); x++) { uint col = (uint)b.GetPixel(x,y).ToArgb(); data[(x - sx) + ((y - sy) * 8)] = (int)((col >> 16) & 0xff) - 128; } } return (data); } public static int[] GetGreenChannelData(Bitmap b, int sx, int sy) { int[] data = new int[8 * 8]; for (int y = sy; y < (sy + 8); y++) { for (int x = sx; x < (sx + 8); x++) { uint col = (uint)b.GetPixel(x, y).ToArgb(); data[(x - sx) + ((y - sy) * 8)] = (int)((col >> 8) & 0xff) - 128; } } return (data); } public static int[] GetBlueChannelData(Bitmap b, int sx, int sy) { int[] data = new int[8 * 8]; for (int y = sy; y < (sy + 8); y++) { for (int x = sx; x < (sx + 8); x++) { uint col = (uint)b.GetPixel(x, y).ToArgb(); data[(x - sx) + ((y - sy) * 8)] = (int)((col >> 0) & 0xff) - 128; } } return (data); } public static int[] Quantize(ref double[] DCTMatrix, ref double[] Q) { int[] DCTMatrixOut = new int[8*8]; for (int u = 0; u < 8; u++) { for (int v = 0; v < 8; v++) { DCTMatrixOut[v + (u * 8)] = (int)Math.Round(DCTMatrix[v + (u * 8)] / Q[v + (u * 8)]); } } return(DCTMatrixOut); } public static double[] DeQuantize(ref int[] DCTMatrix, ref double[] Q) { double[] DCTMatrixOut = new double[8*8]; for (int u = 0; u < 8; u++) { for (int v = 0; v < 8; v++) { DCTMatrixOut[v + (u * 8)] = (double)DCTMatrix[v + (u * 8)] * Q[v + (u * 8)]; } } return(DCTMatrixOut); } public static double[] DCT(ref int[] data) { double[] DCTMatrix = new double[8 * 8]; for (int v = 0; v < 8; v++) { for (int u = 0; u < 8; u++) { double cu = 1; if (u == 0) cu = (1.0 / Math.Sqrt(2.0)); double cv = 1; if (v == 0) cv = (1.0 / Math.Sqrt(2.0)); double sum = 0.0; for (int y = 0; y < 8; y++) { for (int x = 0; x < 8; x++) { double s = data[x + (y * 8)]; double dctVal = Math.Cos((2 * y + 1) * v * Math.PI / 16) * Math.Cos((2 * x + 1) * u * Math.PI / 16); sum += s * dctVal; } } DCTMatrix[u + (v * 8)] = (0.25 * cu * cv * sum); } } return (DCTMatrix); } public static int[] IDCT(ref double[] DCTMatrix) { int[] Matrix = new int[8 * 8]; for (int y = 0; y < 8; y++) { for (int x = 0; x < 8; x++) { double sum = 0; for (int v = 0; v < 8; v++) { for (int u = 0; u < 8; u++) { double cu = 1; if (u == 0) cu = (1.0 / Math.Sqrt(2.0)); double cv = 1; if (v == 0) cv = (1.0 / Math.Sqrt(2.0)); double idctVal = (cu * cv) / 4.0 * Math.Cos((2 * y + 1) * v * Math.PI / 16) * Math.Cos((2 * x + 1) * u * Math.PI / 16); sum += (DCTMatrix[u + (v * 8)] * idctVal); } } Matrix[x + (y * 8)] = (int)Math.Round(sum); } } return (Matrix); } } public class Decoder { public static string Decode(Bitmap b, int expectedLength) { expectedLength *= Encoder.HIDE_COUNT; uint imgWidth = ((uint)b.Width) & ~((uint)7); // Maximum usable X resolution (divisible by 8). uint imgHeight = ((uint)b.Height) & ~((uint)7); // Maximum usable Y resolution (divisible by 8). // Setup the counters and byte data for the message to decode. byte[] codeBytes = new byte[expectedLength]; byte[] outBytes = new byte[expectedLength / Encoder.HIDE_COUNT]; int bitofs = 0; // Current bit position we've decoded too. int totalBits = (codeBytes.Length * 8); // Total number of bits to decode. for (int y = 0; y < imgHeight; y += 8) { for (int x = 0; x < imgWidth; x += 8) { int[] blueData = ImageKey.Encoder.GetBlueChannelData(b, x, y); double[] blueDCT = ImageKey.Encoder.DCT(ref blueData); int[] blueDCTI = ImageKey.Encoder.Quantize(ref blueDCT, ref Encoder.Q2); int[] blueDCTC = ImageKey.Encoder.Quantize(ref blueDCT, ref Encoder.Q); if (bitofs < totalBits) GetBits(ref blueDCTI, ref blueDCTC, ref bitofs, ref totalBits, ref codeBytes); } } bitofs = 0; for (int i = 0; i < (expectedLength / Encoder.HIDE_COUNT) * 8; i++) { int bytePos = (bitofs) >> 3; int bitPos = (bitofs) % 8; byte mask = (byte)(1 << bitPos); List<int> values = new List<int>(); int zeroCount = 0; int oneCount = 0; for (int j = 0; j < Encoder.HIDE_COUNT; j++) { int val = (codeBytes[bytePos + ((expectedLength / Encoder.HIDE_COUNT) * j)] & mask) >> bitPos; values.Add(val); if (val == 0) zeroCount++; else oneCount++; } if (oneCount >= zeroCount) outBytes[bytePos] |= mask; bitofs++; values.Clear(); } return (System.Text.Encoding.ASCII.GetString(outBytes)); } public static void GetBits(ref int[] DCTMatrix, ref int[] CMatrix, ref int bitofs, ref int totalBits, ref byte[] codeBytes) { for (int u = 0; u < 8; u++) { for (int v = 0; v < 8; v++) { if ((u != 0 || v != 0) && CMatrix[v + (u * 8)] != 0 && DCTMatrix[v + (u * 8)] != 0) { if (bitofs < totalBits) { int bytePos = (bitofs) >> 3; int bitPos = (bitofs) % 8; byte mask = (byte)(1 << bitPos); int value = DCTMatrix[v + (u * 8)] & (1 << Encoder.HIDE_BIT_POS); if (value != 0) codeBytes[bytePos] |= mask; bitofs++; } } } } } } } UPDATE: By switching to using a QR Code as the source message and swapping a pair of coefficients in each block instead of bit manipulation I've been able to get the message to survive the transform. However to get the message to come through without corruption I have to adjust both coefficients as well as swap them. For example swapping (3,4) and (4,3) in the DCT matrix and then respectively adding 8 and subtracting 8 as an arbitrary constant seems to work. This survives a re-JPEG'ing of 96 but any form of scaling/cropping destroys the message again. I was hoping that by operating on mid to low frequency values that the message would be preserved even under some light image manipulation.

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  • Counting Alphabetic Characters That Are Contained in an Array with C

    - by Craig
    Hello everyone, I am having trouble with a homework question that I've been working at for quite some time. I don't know exactly why the question is asking and need some clarification on that and also a push in the right direction. Here is the question: (2) Solve this problem using one single subscripted array of counters. The program uses an array of characters defined using the C initialization feature. The program counts the number of each of the alphabetic characters a to z (only lower case characters are counted) and prints a report (in a neat table) of the number of occurrences of each lower case character found. Only print the counts for the letters that occur at least once. That is do not print a count if it is zero. DO NOT use a switch statement in your solution. NOTE: if x is of type char, x-‘a’ is the difference between the ASCII codes for the character in x and the character ‘a’. For example if x holds the character ‘c’ then x-‘a’ has the value 2, while if x holds the character ‘d’, then x-‘a’ has the value 3. Provide test results using the following string: “This is an example of text for exercise (2).” And here is my source code so far: #include<stdio.h> int main() { char c[] = "This is an example of text for exercise (2)."; char d[26]; int i; int j = 0; int k; j = 0; //char s = 97; for(i = 0; i < sizeof(c); i++) { for(s = 'a'; s < 'z'; s++){ if( c[i] == s){ k++; printf("%c,%d\n", s, k); k = 0; } } } return 0; } As you can see, my current solution is a little anemic. Thanks for the help, and I know everyone on the net doesn't necessarily like helping with other people's homework. ;P

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  • Parsing language for both binary and character files

    - by Thorsten S.
    The problem: You have some data and your program needs specified input. For example strings which are numbers. You are searching for a way to transform the original data in a format you need. And the problem is: The source can be anything. It can be XML, property lists, binary which contains the needed data deeply embedded in binary junk. And your output format may vary also: It can be number strings, float, doubles.... You don't want to program. You want routines which gives you commands capable to transform the data in a form you wish. Surely it contains regular expressions, but it is very good designed and it offers capabilities which are sometimes much more easier and more powerful. Something like a super-grep which you can access (!) as program routines, not only as tool. It allows: joining/grouping/merging of results inserting/deleting/finding/replacing write macros which allows to execute a command chain repeatedly meta-grouping (lists-tables-hypertables) Example (No, I am not looking for a solution to this, it is just an example): You want to read xml strings embedded in a binary file with variable length records. Your tool reads the record length and deletes the junk surrounding your text. Now it splits open the xml and extracts the strings. Being Indian number glyphs and containing decimal commas instead of decimal points, your tool transforms it into ASCII and replaces commas with points. Now the results must be stored into matrices of variable length....etc. etc. I am searching for a good language / language-design and if possible, an implementation. Which design do you like or even, if it does not fulfill the conditions, wouldn't you want to miss ? EDIT: The question is if a solution for the problem exists and if yes, which implementations are available. You DO NOT implement your own sorting algorithm if Quicksort, Mergesort and Heapsort is available. You DO NOT invent your own text parsing method if you have regular expressions. You DO NOT invent your own 3D language for graphics if OpenGL/Direct3D is available. There are existing solutions or at least papers describing the problem and giving suggestions. And there are people who may have worked and experienced such problems and who can give ideas and suggestions. The idea that this problem is totally new and I should work out and implement it myself without background knowledge seems for me, I must admit, totally off the mark.

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  • What is the difference between NULL in C++ and null in Java?

    - by Stephano
    I've been trying to figure out why C++ is making me crazy typing NULL. Suddenly it hits me the other day; I've been typing null (lower case) in Java for years. Now suddenly I'm programming in C++ and that little chunk of muscle memory is making me crazy. Wikiperipatetic defines C++ NULL as part of the stddef: A macro that expands to a null pointer constant. It may be defined as ((void*)0), 0 or 0L depending on the compiler and the language. Sun's docs tells me this about Java's "null literal": The null type has one value, the null reference, represented by the literal null, which is formed from ASCII characters. A null literal is always of the null type. So this is all very nice. I know what a null pointer reference is, and thank you for the compiler notes. Now I'm a little fuzzy on the idea of a literal in Java so I read on... A literal is the source code representation of a fixed value; literals are represented directly in your code without requiring computation. There's also a special null literal that can be used as a value for any reference type. null may be assigned to any variable, except variables of primitive types. There's little you can do with a null value beyond testing for its presence. Therefore, null is often used in programs as a marker to indicate that some object is unavailable. Ok, so I think I get it now. In C++ NULL is a macro that, when compiled, defines the null pointer constant. In Java, null is a fixed value that any non-primitive can be assigned too; great for testing in a handy if statement. Java does not have pointers, so I can see why they kept null a simple value rather than anything fancy. But why did java decide to change the all caps NULL to null? Furthermore, am I missing anything here?

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  • Understanding WebRequest

    - by Nai
    I found this snippet of code here that allows you to log into a website and get the response from the logged in page. However, I'm having trouble understanding all the part of the code. I've tried my best to fill in whatever I understand so far. Hope you guys can fill in the blanks for me. Thanks string nick = "mrbean"; string password = "12345"; //this is the query data that is getting posted by the website. //the query parameters 'nick' and 'password' must match the //name of the form you're trying to log into. you can find the input names //by using firebug and inspecting the text field string postData = "nick=" + nick + "&password=" + password; // this puts the postData in a byte Array with a specific encoding //Why must the data be in a byte array? byte[] data = Encoding.ASCII.GetBytes(postData); // this basically creates the login page of the site you want to log into WebRequest request = WebRequest.Create("http://www.mrbeanandme.com/login/"); // im guessing these parameters need to be set but i dont why? request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = data.Length; // this opens a stream for writing the post variables. // im not sure what a stream class does. need to do some reading into this. Stream stream = request.GetRequestStream(); // you write the postData to the website and then close the connection? stream.Write(data, 0, data.Length); stream.Close(); // this receives the response after the log in WebResponse response = request.GetResponse(); stream = response.GetResponseStream(); // i guess you need a stream reader to read a stream? StreamReader sr = new StreamReader(stream); // this outputs the code to console and terminates the program Console.WriteLine(sr.ReadToEnd()); Console.ReadLine();

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  • Am I just not understanding TDD unit testing (Asp.Net MVC project)?

    - by KallDrexx
    I am trying to figure out how to correctly and efficiently unit test my Asp.net MVC project. When I started on this project I bought the Pro ASP.Net MVC, and with that book I learned about TDD and unit testing. After seeing the examples, and the fact that I work as a software engineer in QA in my current company, I was amazed at how awesome TDD seemed to be. So I started working on my project and went gun-ho writing unit tests for my database layer, business layer, and controllers. Everything got a unit test prior to implementation. At first I thought it was awesome, but then things started to go downhill. Here are the issues I started encountering: I ended up writing application code in order to make it possible for unit tests to be performed. I don't mean this in a good way as in my code was broken and I had to fix it so the unit test pass. I mean that abstracting out the database to a mock database is impossible due to the use of linq for data retrieval (using the generic repository pattern). The reason is that with linq-sql or linq-entities you can do joins just by doing: var objs = select p from _container.Projects select p.Objects; However, if you mock the database layer out, in order to have that linq pass the unit test you must change the linq to be var objs = select p from _container.Projects join o in _container.Objects on o.ProjectId equals p.Id select o; Not only does this mean you are changing your application logic just so you can unit test it, but you are making your code less efficient for the sole purpose of testability, and getting rid of a lot of advantages using an ORM has in the first place. Furthermore, since a lot of the IDs for my models are database generated, I proved to have to write additional code to handle the non-database tests since IDs were never generated and I had to still handle those cases for the unit tests to pass, yet they would never occur in real scenarios. Thus I ended up throwing out my database unit testing. Writing unit tests for controllers was easy as long as I was returning views. However, the major part of my application (and the one that would benefit most from unit testing) is a complicated ajax web application. For various reasons I decided to change the app from returning views to returning JSON with the data I needed. After this occurred my unit tests became extremely painful to write, as I have not found any good way to write unit tests for non-trivial json. After pounding my head and wasting a ton of time trying to find a good way to unit test the JSON, I gave up and deleted all of my controller unit tests (all controller actions are focused on this part of the app so far). So finally I was left with testing the Service layer (BLL). Right now I am using EF4, however I had this issue with linq-sql as well. I chose to do the EF4 model-first approach because to me, it makes sense to do it that way (define my business objects and let the framework figure out how to translate it into the sql backend). This was fine at the beginning but now it is becoming cumbersome due to relationships. For example say I have Project, User, and Object entities. One Object must be associated to a project, and a project must be associated to a user. This is not only a database specific rule, these are my business rules as well. However, say I want to do a unit test that I am able to save an object (for a simple example). I now have to do the following code just to make sure the save worked: User usr = new User { Name = "Me" }; _userService.SaveUser(usr); Project prj = new Project { Name = "Test Project", Owner = usr }; _projectService.SaveProject(prj); Object obj = new Object { Name = "Test Object" }; _objectService.SaveObject(obj); // Perform verifications There are many issues with having to do all this just to perform one unit test. There are several issues with this. For starters, if I add a new dependency, such as all projects must belong to a category, I must go into EVERY single unit test that references a project, add code to save the category then add code to add the category to the project. This can be a HUGE effort down the road for a very simple business logic change, and yet almost none of the unit tests I will be modifying for this requirement are actually meant to test that feature/requirement. If I then add verifications to my SaveProject method, so that projects cannot be saved unless they have a name with at least 5 characters, I then have to go through every Object and Project unit test to make sure that the new requirement doesn't make any unrelated unit tests fail. If there is an issue in the UserService.SaveUser() method it will cause all project, and object unit tests to fail and it the cause won't be immediately noticeable without having to dig through the exceptions. Thus I have removed all service layer unit tests from my project. I could go on and on, but so far I have not seen any way for unit testing to actually help me and not get in my way. I can see specific cases where I can, and probably will, implement unit tests, such as making sure my data verification methods work correctly, but those cases are few and far between. Some of my issues can probably be mitigated but not without adding extra layers to my application, and thus making more points of failure just so I can unit test. Thus I have no unit tests left in my code. Luckily I heavily use source control so I can get them back if I need but I just don't see the point. Everywhere on the internet I see people talking about how great TDD unit tests are, and I'm not just talking about the fanatical people. The few people who dismiss TDD/Unit tests give bad arguments claiming they are more efficient debugging by hand through the IDE, or that their coding skills are amazing that they don't need it. I recognize that both of those arguments are utter bullocks, especially for a project that needs to be maintainable by multiple developers, but any valid rebuttals to TDD seem to be few and far between. So the point of this post is to ask, am I just not understanding how to use TDD and automatic unit tests?

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  • How can I group an array of rectangles into "Islands" of connected regions?

    - by Eric
    The problem I have an array of java.awt.Rectangles. For those who are not familiar with this class, the important piece of information is that they provide an .intersects(Rectangle b) function. I would like to write a function that takes this array of Rectangles, and breaks it up into groups of connected rectangles. Lets say for example, that these are my rectangles (constructor takes the arguments x, y, width,height): Rectangle[] rects = new Rectangle[] { new Rectangle(0, 0, 4, 2), //A new Rectangle(1, 1, 2, 4), //B new Rectangle(0, 4, 8, 2), //C new Rectangle(6, 0, 2, 2) //D } A quick drawing shows that A intersects B and B intersects C. D intersects nothing. A tediously drawn piece of ascii art does the job too: +-------+ +---+ ¦A+---+ ¦ ¦ D ¦ +-+---+-+ +---+ ¦ B ¦ +-+---+---------+ ¦ +---+ C ¦ +---------------+ Therefore, the output of my function should be: new Rectangle[][]{ new Rectangle[] {A,B,C}, new Rectangle[] {D} } The failed code This was my attempt at solving the problem: public List<Rectangle> getIntersections(ArrayList<Rectangle> list, Rectangle r) { List<Rectangle> intersections = new ArrayList<Rectangle>(); for(Rectangle rect : list) { if(r.intersects(rect)) { list.remove(rect); intersections.add(rect); intersections.addAll(getIntersections(list, rect)); } } return intersections; } public List<List<Rectangle>> mergeIntersectingRects(Rectangle... rectArray) { List<Rectangle> allRects = new ArrayList<Rectangle>(rectArray); List<List<Rectangle>> groups = new ArrayList<ArrayList<Rectangle>>(); for(Rectangle rect : allRects) { allRects.remove(rect); ArrayList<Rectangle> group = getIntersections(allRects, rect); group.add(rect); groups.add(group); } return groups; } Unfortunately, there seems to be an infinite recursion loop going on here. My uneducated guess would be that java does not like me doing this: for(Rectangle rect : allRects) { allRects.remove(rect); //... } Can anyone shed some light on the issue?

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  • Decode base64 data as array in Python

    - by skerit
    I'm using this handy Javascript function to decode a base64 string and get an array in return. This is the string: base64_decode_array('6gAAAOsAAADsAAAACAEAAAkBAAAKAQAAJgEAACcBAAAoAQAA') This is what's returned: 234,0,0,0,235,0,0,0,236,0,0,0,8,1,0,0,9,1,0,0,10,1,0,0,38,1,0,0,39,1,0,0,40,1,0,0 The problem is I don't really understand the javascript function: var base64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split(""); var base64inv = {}; for (var i = 0; i < base64chars.length; i++) { base64inv[base64chars[i]] = i; } function base64_decode_array (s) { // remove/ignore any characters not in the base64 characters list // or the pad character -- particularly newlines s = s.replace(new RegExp('[^'+base64chars.join("")+'=]', 'g'), ""); // replace any incoming padding with a zero pad (the 'A' character is zero) var p = (s.charAt(s.length-1) == '=' ? (s.charAt(s.length-2) == '=' ? 'AA' : 'A') : ""); var r = []; s = s.substr(0, s.length - p.length) + p; // increment over the length of this encrypted string, four characters at a time for (var c = 0; c < s.length; c += 4) { // each of these four characters represents a 6-bit index in the base64 characters list // which, when concatenated, will give the 24-bit number for the original 3 characters var n = (base64inv[s.charAt(c)] << 18) + (base64inv[s.charAt(c+1)] << 12) + (base64inv[s.charAt(c+2)] << 6) + base64inv[s.charAt(c+3)]; // split the 24-bit number into the original three 8-bit (ASCII) characters r.push((n >>> 16) & 255); r.push((n >>> 8) & 255); r.push(n & 255); } // remove any zero pad that was added to make this a multiple of 24 bits return r; } What's the function of those "<<<" and "" characters. Or is there a function like this for Python?

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  • Scalable Database Tagging Schema

    - by Longpoke
    EDIT: To people building tagging systems. Don't read this. It is not what you are looking for. I asked this when I wasn't aware that RDBMS all have their own optimization methods, just use a simple many to many scheme. I have a posting system that has millions of posts. Each post can have an infinite number of tags associated with it. Users can create tags which have notes, date created, owner, etc. A tag is almost like a post itself, because people can post notes about the tag. Each tag association has an owner and date, so we can see who added the tag and when. My question is how can I implement this? It has to be fast searching posts by tag, or tags by post. Also, users can add tags to posts by typing the name into a field, kind of like the google search bar, it has to fill in the rest of the tag name for you. I have 3 solutions at the moment, but not sure which is the best, or if there is a better way. Note that I'm not showing the layout of notes since it will be trivial once I get a proper solution for tags. Method 1. Linked list tagId in post points to a linked list in tag_assoc, the application must traverse the list until flink=0 post: id, content, ownerId, date, tagId, notesId tag_assoc: id, tagId, ownerId, flink tag: id, name, notesId Method 2. Denormalization tags is simply a VARCHAR or TEXT field containing a tab delimited array of tagId:ownerId. It cannot be a fixed size. post: id, content, ownerId, date, tags, notesId tag: id, name, notesId Method 3. Toxi (from: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html, also same thing here: http://stackoverflow.com/questions/20856/how-do-you-recommend-implementing-tags-or-tagging) post: id, content, ownerId, date, notesId tag_assoc: ownerId, tagId, postId tag: id, name, notesId Method 3 raises the question, how fast will it be to iterate through every single row in tag_assoc? Methods 1 and 2 should be fast for returning tags by post, but for posts by tag, another lookup table must be made. The last thing I have to worry about is optimizing searching tags by name, I have not worked that out yet. I made an ASCII diagram here: http://pastebin.com/f1c4e0e53

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