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  • Problem of using cin twice.

    - by gc
    Here is the code: string str; cinstr; cout<<"first input:"<<str<<endl; getline(cin, str); cout<<"line input:"<<str<<endl; The result is that getline never pauses for user input, therefore the second output is always empty. After spending some time on it, I realized after the first call "cinstr", it seems '\n' is still stored in cin (using cin.peek() to check), which ends getline immediately. The solution will be adding one more line between the first usage and the second one: cin.ignore(numeric_limits::max(), '\n'); However, I still don't understand, why is '\n' left there after the first call? What does istream& operator really do?

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  • Socket.recv works but not gets or read?

    - by Earlz
    Hello I've been messing around with Sockets in Ruby some and came across some example code that I tried modifying and broke. I want to know why it's broken. Server: require "socket" dts = TCPServer.new('127.0.0.1', 20000) loop do Thread.start(dts.accept) do |s| print(s, " is accepted\n") s.write(Time.now) print(s, " is gone\n") s.close end end Client that works: require 'socket' streamSock = TCPSocket.new( "127.0.0.1", 20000 ) streamSock.print( "Hello\n" ) str = streamSock.recv( 100 ) print str streamSock.close Client that is broken require 'socket' streamSock = TCPSocket.new( "127.0.0.1", 20000 ) streamSock.print( "Hello\n" ) str=streamSock.read #this line modified print str streamSock.close I know that the streamSock.print is unnecessary (as well as the naming scheme being non-ruby) but I don't understand why read doesn't work while recv does, Why is this?

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  • .NET: Is there a way to finagle a default namespace in an XPath 1.0 query?

    - by Cheeso
    I'm building a tool that performs xpath 1.0 queries on XHTML documents. The requirement to use a namespace prefix in the query is killing me. The query looks like this: html/body/div[@class='contents']/div[@class='body']/ div[@class='pgdbbyauthor']/h2[a[@name][starts-with(.,'Quick')]]/ following-sibling::ul[1]/li/a (all on one line) ...which is bad enough, except because it's xpath 1.0, I need to use an explicit namespace prefix on each QName, so it looks like this: ns1:html/ns1:body/ns1:div[@class='contents']/ns1:div[@class='body']/ ns1:div[@class='pgdbbyauthor']/ns1:h2[ns1:a[@name][starts-with(.,'Quick')]]/ following-sibling::ns1:ul[1]/ns1:li/ns1:a To set up the query, I do something like this: var xpathDoc = new XPathDocument(new StringReader(theText)); var nav = xpathDoc.CreateNavigator(); var xmlns = new XmlNamespaceManager(nav.NameTable); foreach (string prefix in xmlNamespaces.Keys) xmlns.AddNamespace(prefix, xmlNamespaces[prefix]); XPathNodeIterator selection = nav.Select(xpathExpression, xmlns); But what I want is for the xpathExpression to use the implicit default namespace. Is there a way for me to transform the unadorned xpath expression, after it's been written, to inject a namespace prefix for each element name in the query? I'm thinking, anything between two slashes, I could inject a prefix there. Excepting of course axis names like "parent::" and "preceding-sibling::" . And wildcards. That's what I mean by "finagle a default namespace". Is this hack gonna work? Addendum Here's what I mean. suppose I have an xpath expression, and before passing it to nav.Select(), I transform it. Something like this: string FixupWithDefaultNamespace(string expr) { string s = expr; s = Regex.Replace(s, "^(?!::)([^/:]+)(?=/)", "ns1:$1"); // beginning s = Regex.Replace(s, "/([^/:]+)(?=/)", "/ns1:$1"); // stanza s = Regex.Replace(s, "::([A-Za-z][^/:*]*)(?=/)", "::ns1:$1"); // axis specifier s = Regex.Replace(s, "\\[([A-Za-z][^/:*\\(]*)(?=[\\[\\]])", "[ns1:$1"); // predicate s = Regex.Replace(s, "/([A-Za-z][^/:]*)(?!<::)$", "/ns1:$1"); // end s = Regex.Replace(s, "^([A-Za-z][^/:]*)$", "ns1:$1"); // edge case s = Regex.Replace(s, "([-A-Za-z]+)\\(([^/:\\.,\\)]+)(?=[,\\)])", "$1(ns1:$2"); // xpath functions return s; } This actually works for simple cases I tried. To use the example from above - if the input is the first xpath expression, the output I get is the 2nd one, with all the ns1 prefixes. The real question is, is it hopeless to expect this Regex.Replace approach to work, as the xpath expressions get more complicated?

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  • How to share a variable between two classes?

    - by Altefquatre
    How would you share the same object between two other objects? For instance, I'd like something in that flavor: class A { private string foo_; // It could be any other class/struct too (Vector3, Matrix...) public A (string shared) { this.foo_ = shared; } public void Bar() { this.foo_ = "changed"; } } ... // inside main string str = "test"; A a = new A(str); Console.WriteLine(str); // "test" a.Bar(); Console.WriteLine(str); // I get "test" instead of "changed"... :( I read there is some ref/out stuff, but I couldn't get what I'm asking here. I could only apply some changes in the methods scope where I was using ref/out arguments... I also read we could use pointers, but is there no other way to do it?

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  • C++ Check Substring of a String

    - by user69514
    I'm trying to check whether or not the second argument in my program is a substring of the first argument. The problem is that it only work if the substring starts with the same letter of the string. .i.e Michigan - Mich (this works) Michigan - Mi (this works) Michigan - igan (this doesn't work) #include <stdio.h> #include <string.h> #include <string> using namespace std; bool my_strstr( string str, string sub ) { bool flag = true; int startPosition = -1; char subStart = str.at(0); char strStart; //find starting position for(int i=0; i<str.length(); i++){ if(str.at(i) == subStart){ startPosition = i; break; } } for(int i=0; i<sub.size(); i++){ if(sub.at(i) != str.at(startPosition)){ flag = false; break; } startPosition++; } return flag; } int main(int argc, char **argv){ if (argc != 3) { printf ("Usage: check <string one> <string two>\n"); } string str1 = argv[1]; string str2 = argv[2]; bool result = my_strstr(str1, str2); if(result == 1){ printf("%s is a substring of %s\n", argv[2], argv[1]); } else{ printf("%s is not a substring of %s\n", argv[2], argv[1]); } return 0; }

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  • Determine if a string contains only alphanumeric characters (or a space)

    - by dreamlax
    I'm learning C++ and I am writing a function that determines whether a string contains only alphanumeric characters and spaces. I suppose I am effectively testing whether it matches the regular expression ^[[:alnum:] ]+$ but without using regular expressions. I have seen a lot of algorithms revolve around iterators, so I tried to find a solution that made use of iterators, and this is what I have: #include <algorithm> static inline bool is_not_alnum_space(char c) { return !(isalpha(c) || isdigit(c) || (c == ' ')); } bool string_is_valid(const std::string &str) { return find_if(str.begin(), str.end(), is_not_alnum_space) == str.end(); } Is there a better solution, or a “more C++” way to do this?

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  • Jakarta Regexp 1.5 Backreferences?

    - by Matt Smith
    Why does this match: String str = "099.9 102.2" + (char) 0x0D; RE re = new RE("^([0-9]{3}.[0-9]) ([0-9]{3}.[0-9])\r$"); System.out.println(re.match(str)); But this does not: String str = "099.9 102.2" + (char) 0x0D; RE re = new RE("^([0-9]{3}.[0-9]) \1\r$"); System.out.println(re.match(str)); The back references don't seem to be working... What am I missing?

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  • Javascript callback function does not work in IE8!

    - by Abhishek
    I have a callback function in my open social application which fetches remote date. This works perfect on Crome and Mozila browers but not in IE8. Following is the example for the same, help will be appriciated: This funcation: gadgets.io.makeRequest(url, response, params) makes the callback call and following function process the responce: function response(obj) { var str = obj.text; var offerDtlPg = str.substr(0, str.length); document.getElementById('pplOfrDetls').innerHTML = offerDtlPg; };

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  • struct and rand()

    - by teoz
    I have a struct with an array of 100 int (b) and a variable of type int (a) I have a function that checks if the value of "a" is in the array and i have generated the array elements and the variable with random values. but it doesn't work can someone help me fix it? #include <stdio.h> #include <stdlib.h> #include <time.h> typedef struct { int a; int b[100]; } h; int func(h v){ int i; for (i=0;i<100;i++){ if(v.b[i]==v.a) return 1; else return 0; } } int main(int argc, char** argv) { h str; srand(time(0)); int i; for(i=0;0<100;i++){ str.b[i]=(rand() % 10) + 1; } str.a=(rand() % 10) + 1; str.a=1; printf("%d\n",func(str)); return 0; }

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  • Python 3.3 Webserver restarting problems

    - by IPDGino
    I have made a simple webserver in python, and had some problems with it before as described here: Python (3.3) Webserver script with an interesting error In that question, the answer was to use a While True: loop so that any crashes or errors would be resolved instantly, because it would just start itself again. I've used this for a while, and still want to make the server restart itself every few minutes, but on Linux for some reason it won't work for me. On windows the code below works fine, but on linux it keeps saying Handler class up here ... ... class Server: def __init__(self): self.server_class = HTTPServer self.server_adress = ('MY IP GOES HERE, or localhost', 8080) global httpd httpd = self.server_class(self.server_adress, Handler) self.main() def main(self): if count > 1: global SERVER_UP_SINCE HOUR_CHECK = int(((count - 1) * RESTART_INTERVAL) / 60) SERVER_UPTIME = str(HOUR_CHECK) + " MINUTES" if HOUR_CHECK > 60: minutes = int(HOUR_CHECK % 60) hours = int(HOUR_CHECK // 60) SERVER_UPTIME = ("%s HOURS, %s MINUTES" % (str(hours), str(minutes))) SERVING_ON_ADDR = self.server_adress SERVER_UP_SINCE = str(SERVER_UP_SINCE) SERVER_RESTART_NUMBER = count - 1 print(""" SERVER INFO ------------------------------------- SERVER_UPTIME: %s SERVER_UP_SINCE: %s TOTAL_FILES_SERVED: %d SERVING_ON_ADDR: %s SERVER_RESTART_NUMBER: %s \n\nSERVER HAS RESTARTED """ % (SERVER_UPTIME, SERVER_UP_SINCE, TOTAL_FILES, SERVING_ON_ADDR, SERVER_RESTART_NUMBER)) else: print("SERVER_BOOT=1\nSERVER_ONLINE=TRUE\nRESTART_LOOP=TRUE\nSERVING_ON_ADDR:%s" % str(self.server_adress)) while True: try: httpd.serve_forever() except KeyboardInterrupt: print("Shutting down...") break httpd.shutdown() httpd.socket.close() raise(SystemExit) return def server_restart(): """If you want the restart timer to be longer, replace the number after the RESTART_INTERVAL variable""" global RESTART_INTERVAL RESTART_INTERVAL = 10 threading.Timer(RESTART_INTERVAL, server_restart).start() global count count = count + 1 instance = Server() if __name__ == "__main__": global SERVER_UP_SINCE SERVER_UP_SINCE = strftime("%d-%m-%Y %H:%M:%S", gmtime()) server_restart() Basically, I make a thread to restart it every 10 seconds (For testing purposes) and start the server. After ten seconds it will say File "/home/username/Desktop/Webserver/server.py", line 199, in __init__ httpd = self.server_class(self.server_adress, Handler) File "/usr/lib/python3.3/socketserver.py", line 430, in __init__ self.server_bind() File "/usr/lib/python3.3/http/server.py", line 135, in server_bind socketserver.TCPServer.server_bind(self) File "/usr/lib/python3.3/socketserver.py", line 441, in server_bind self.socket.bind(self.server_address) OSError: [Errno 98] Address already in use As you can see in the except KeyboardInterruption line, I tried everything to make the server stop, and the program stop, but it will NOT stop. But the thing I really want to know is how to make this server able to restart, without giving some wonky errors.

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  • Data Access Layer in an ASP.NET website

    - by user3519124
    :) i have a DAL class file in my project, that my teacher sent me and explained to me but i did not really understand it. It has number of functions, and I understand only few of them, like with connecting to the database or creating a command object but there are 2 that I dont understand: public static DataTable GetTable(string str) { OleDbConnection con = DAL.GetConnection(); OleDbCommand cmd = DAL.GetCommand(con, str); DataTable dt = new DataTable(); OleDbDataAdapter adp = new OleDbDataAdapter(); adp.SelectCommand = cmd; adp.Fill(dt); return dt; } public static int ExecuteNonQuery(string str) { int num = -1; OleDbConnection con = DAL.GetConnection(); con.Open(); if (con.State == ConnectionState.Open) { OleDbCommand cmd = DAL.GetCommand(con, str); num = cmd.ExecuteNonQuery(); con.Close(); } return num; } thank you :)

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  • Why is phpseclib producing incompatible certs?

    - by chacham15
    Why is it that when I try to use a certificate/key pair generated from phpseclib, the OpenSSL server code errors out? Certs/Keys generated from OpenSSL work fine. How do I fix this? Certificate/Key Generation taken straight from phpseclib documentation: <?php include('File/X509.php'); include('Crypt/RSA.php'); // create private key / x.509 cert for stunnel / website $privKey = new Crypt_RSA(); extract($privKey-createKey()); $privKey-loadKey($privatekey); $pubKey = new Crypt_RSA(); $pubKey-loadKey($publickey); $pubKey-setPublicKey(); $subject = new File_X509(); $subject-setDNProp('id-at-organizationName', 'phpseclib demo cert'); //$subject-removeDNProp('id-at-organizationName'); $subject-setPublicKey($pubKey); $issuer = new File_X509(); $issuer-setPrivateKey($privKey); $issuer-setDN($subject-getDN()); $x509 = new File_X509(); //$x509-setStartDate('-1 month'); // default: now //$x509-setEndDate('+1 year'); // default: +1 year $result = $x509-sign($issuer, $subject); echo "the stunnel.pem contents are as follows:\r\n\r\n"; echo $privKey-getPrivateKey(); echo "\r\n"; echo $x509-saveX509($result); echo "\r\n"; ? OpenSSL sample SSL server taken straight from OpenSSL example code: #include <stdio.h #include <unistd.h #include <stdlib.h #include <memory.h #include <errno.h #include <sys/types.h #include <sys/socket.h #include <netinet/in.h #include <arpa/inet.h #include <netdb.h #include <openssl/rsa.h /* SSLeay stuff */ #include <openssl/crypto.h #include <openssl/x509.h #include <openssl/pem.h #include <openssl/ssl.h #include <openssl/err.h #define CHK_NULL(x) if ((x)==NULL) exit (1) #define CHK_ERR(err,s) if ((err)==-1) { perror(s); exit(1); } #define CHK_SSL(err) if ((err)==-1) { ERR_print_errors_fp(stderr); exit(2); } int main (int argc, char *argv[]) { int err; int listen_sd; int sd; struct sockaddr_in sa_serv; struct sockaddr_in sa_cli; size_t client_len; SSL_CTX* ctx; SSL* ssl; X509* client_cert; char* str; char buf [4096]; SSL_METHOD *meth; /* SSL preliminaries. We keep the certificate and key with the context. */ SSL_load_error_strings(); SSLeay_add_ssl_algorithms(); meth = SSLv23_server_method(); ctx = SSL_CTX_new (meth); if (!ctx) { ERR_print_errors_fp(stderr); exit(2); } if (SSL_CTX_use_certificate_file(ctx, argv[1], SSL_FILETYPE_PEM) <= 0) { ERR_print_errors_fp(stderr); exit(3); } if (SSL_CTX_use_PrivateKey_file(ctx, argv[2], SSL_FILETYPE_PEM) <= 0) { ERR_print_errors_fp(stderr); exit(4); } if (!SSL_CTX_check_private_key(ctx)) { fprintf(stderr,"Private key does not match the certificate public key\n"); exit(5); } /* ----------------------------------------------- */ /* Prepare TCP socket for receiving connections */ listen_sd = socket (AF_INET, SOCK_STREAM, 0); CHK_ERR(listen_sd, "socket"); memset (&sa_serv, '\0', sizeof(sa_serv)); sa_serv.sin_family = AF_INET; sa_serv.sin_addr.s_addr = INADDR_ANY; sa_serv.sin_port = htons (1111); /* Server Port number */ err = bind(listen_sd, (struct sockaddr*) &sa_serv, sizeof (sa_serv)); CHK_ERR(err, "bind"); /* Receive a TCP connection. */ err = listen (listen_sd, 5); CHK_ERR(err, "listen"); client_len = sizeof(sa_cli); sd = accept (listen_sd, (struct sockaddr*) &sa_cli, (unsigned int*)&client_len); CHK_ERR(sd, "accept"); close (listen_sd); printf ("Connection from %lx, port %x\n", sa_cli.sin_addr.s_addr, sa_cli.sin_port); /* ----------------------------------------------- */ /* TCP connection is ready. Do server side SSL. */ ssl = SSL_new (ctx); CHK_NULL(ssl); SSL_set_fd (ssl, sd); err = SSL_accept (ssl); CHK_SSL(err); /* Get the cipher - opt */ printf ("SSL connection using %s\n", SSL_get_cipher (ssl)); /* Get client's certificate (note: beware of dynamic allocation) - opt */ client_cert = SSL_get_peer_certificate (ssl); if (client_cert != NULL) { printf ("Client certificate:\n"); str = X509_NAME_oneline (X509_get_subject_name (client_cert), 0, 0); CHK_NULL(str); printf ("\t subject: %s\n", str); OPENSSL_free (str); str = X509_NAME_oneline (X509_get_issuer_name (client_cert), 0, 0); CHK_NULL(str); printf ("\t issuer: %s\n", str); OPENSSL_free (str); /* We could do all sorts of certificate verification stuff here before deallocating the certificate. */ X509_free (client_cert); } else printf ("Client does not have certificate.\n"); /* DATA EXCHANGE - Receive message and send reply. */ err = SSL_read (ssl, buf, sizeof(buf) - 1); CHK_SSL(err); buf[err] = '\0'; printf ("Got %d chars:'%s'\n", err, buf); err = SSL_write (ssl, "I hear you.", strlen("I hear you.")); CHK_SSL(err); /* Clean up. */ close (sd); SSL_free (ssl); SSL_CTX_free (ctx); return 1; } /* EOF - serv.cpp */ This program errors with: (the error is printed out on the call to SSL_write) Connection from 100007f, port a7ff SSL connection using (NONE) Client does not have certificate. Got 0 chars:'' 82673:error:1409E0E5:SSL routines:SSL3_WRITE_BYTES:ssl handshake failure:/SourceCache/OpenSSL098/OpenSSL098-44/src/ssl/s3_pkt.c:539: Here is the relevant code referenced by the error: int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len) { const unsigned char *buf=buf_; unsigned int tot,n,nw; int i; s-rwstate=SSL_NOTHING; tot=s-s3-wnum; s-s3-wnum=0; if (SSL_in_init(s) && !s-in_handshake) { i=s-handshake_func(s); if (i < 0) return(i); if (i == 0) { SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE); return -1; } } ...etc

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  • Get index of nth occurrence of char in a string

    - by StickFigs
    I'm trying to make a function that returns the index of the Nth occurrence of a given char in a string. Here is my attempt: private int IndexOfNth(string str, char c, int n) { int index = str.IndexOf(c) + 1; if (index >= 0) { string temp = str.Substring(index, str.Length - index); for (int j = 1; j < n; j++) { index = temp.IndexOf(c) + 1; if (index < 0) { return -1; } temp = temp.Substring(index, temp.Length - index); } index = index + (str.Length); } return index; } This should find the first occurrence, chop off that front part of the string, find the first occurrence from the new substring, and on and on until it gets the index of the nth occurrence. However I failed to consider how the index of the final substring is going to be offset from the original actual index in the original string. How do I make this work? Also as a side question, if I want the char to be the tab character do I pass this function '\t' or what?

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  • [PHP] strtr function OS-reltated problem

    - by Casidiablo
    Hello there! I have this funtion that converts all special chars to uppercase: function uc_latin1($str) { if(!defined("LATIN1_UC_CHARS")) define("LATIN1_UC_CHARS", "ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝ"); if(!defined("LATIN1_LC_CHARS")) define("LATIN1_LC_CHARS", "àáâãäåæçèéêëìíîïðñòóôõöøùúûüý"); $str = strtoupper ( strtr ( $str, LATIN1_LC_CHARS, LATIN1_UC_CHARS ) ); return $str; } This function works fine in my development PC (which runs Windows XP)... but, when I test it in the production server (running Redhat Linux) it does not uppercase the string. The string is ISO-8859-1 encoded. How can I make it work in Linux too? Thanks for reading.

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  • help with reflections and annotations in java

    - by Yonatan
    Hello Internet ! I'm having trouble with doubling up on my code for no reason other than my own lack of ability to do it more efficiently... `for (Method curr: all){ if (curr.isAnnotationPresent(anno)){ if (anno == Pre.class){ for (String str : curr.getAnnotation(Pre.class).value()){ if (str.equals(method.getName()) && curr.getReturnType() == boolean.class && curr.getParameterTypes().length == 0){ toRun.add(curr); } } } if (anno == Post.class) { for (String str : curr.getAnnotation(Post.class).value()){ if (str.equals(method.getName()) && curr.getReturnType() == boolean.class && curr.getParameterTypes().length == 0){ toRun.add(curr); } } } } }` anno is a parameter - Class, and Pre and Post are my annotations, both have a value() which is an array of strings. Of course, this is all due to the fact that i let Eclipse auto fill code that i don't understand yet.

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  • simple question on C

    - by lego69
    I have this snippet of the code char *str = “123”; if(str[0] == 1) printf("Hello\n"); why I can't receive my Hello thanks in advance! how exactly compiler does this comparison if(str[0] == 1)?

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  • C++: sizeof for array length

    - by Rosarch
    Let's say I have a macro called LengthOf(array): sizeof array / sizeof array[0] When I make a new array of size 23, shouldn't I get 23 back for LengthOf? WCHAR* str = new WCHAR[23]; str[22] = '\0'; size_t len = LengthOf(str); // len == 4 Why does len == 4? UPDATE: I made a typo, it's a WCHAR*, not a WCHAR**.

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  • string parsing and substring in c

    - by Josh
    I'm trying to parse the string below in a good way so I can get the sub-string stringI-wantToGet: const char *str = "Hello \"FOO stringI-wantToGet BAR some other extra text"; str will vary in length but always same pattern - FOO and BAR What I had in mind was something like: const char *str = "Hello \"FOO stringI-wantToGet BAR some other extra text"; char *probe, *pointer; probe = str; while(probe != '\n'){ if(probe = strstr("\"FOO")!=NULL) probe++ else probe = ""; // Nulterm part if(pointer = strchr(probe, ' ')!=NULL) pointer = '\0'; // not sure here, I was planning to separate it with \0's } Any help will be appreciate it.

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  • Access ConfigurationSection from ConfigurationElement

    - by shivesh
    I have a configuration class that maps web.config, something like that: public class SiteConfigurationSection : ConfigurationSection { [ConfigurationProperty("defaultConnectionStringName", DefaultValue = "LocalSqlServer")] public string DefaultConnectionStringName { get { return (string)base["defaultConnectionStringName"]; } set { base["defaultConnectionStringName"] = value; } } [ConfigurationProperty("Module", IsRequired = true)] public ModuleElement Module { get { return (ModuleElement)base["Module"]; } } } public class ModuleElement : ConfigurationElement { [ConfigurationProperty("connectionStringName")] public string ConnectionStringName { get { return (string)base["connectionStringName"]; } set { base["connectionStringName"] = value; } } public string ConnectionString { get { string str; if (string.IsNullOrEmpty(this.ConnectionStringName)) { str =//GET THE DefaultConnectionStringName from SiteConfigurationSection; } else str = this.ConnectionStringName; return WebConfigurationManager.ConnectionStrings[str].ConnectionString; } } } Meaning if connection string name value is missing in Module section in web.config file, the value should be read from configurationsection. How to do that?

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  • Custom string class (C++)

    - by Sanctus2099
    Hey guys. I'm trying to write my own C++ String class for educational and need purposes. The first thing is that I don't know that much about operators and that's why I want to learn them. I started writing my class but when I run it it blocks the program but does not do any crash. Take a look at the following code please before reading further: class CString { private: char* cstr; public: CString(); CString(char* str); CString(CString& str); ~CString(); operator char*(); operator const char*(); CString operator+(const CString& q)const; CString operator=(const CString& q); }; First of all I'm not so sure I declared everything right. I tried googleing about it but all the tutorials about overloading explain the basic ideea which is very simple but lack to explain how and when each thing is called. For instance in my = operator the program calls CString(CString& str); but I have no ideea why. I have also attached the cpp file below: CString::CString() { cstr=0; } CString::CString(char *str) { cstr=new char[strlen(str)]; strcpy(cstr,str); } CString::CString(CString& q) { if(this==&q) return; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } CString::~CString() { if(cstr) delete[] cstr; } CString::operator char*() { return cstr; } CString::operator const char* () { return cstr; } CString CString::operator +(const CString &q) const { CString s; s.cstr = new char[strlen(cstr)+strlen(q.cstr)+1]; strcpy(s.cstr,cstr); strcat(s.cstr,q.cstr); return s; } CString CString::operator =(const CString &q) { if(this!=&q) { if(cstr) delete[] cstr; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } return *this; } For testing I used a code just as simple as this CString a = CString("Hello") + CString(" World"); printf(a); I tried debugging it but at a point I get lost. First it calls the constructor 2 times for "hello" and for " world". Then it get's in the + operator which is fine. Then it calls the constructor for the empty string. After that it get's into "CString(CString& str)" and now I'm lost. Why is this happening? After this I noticed my string containing "Hello World" is in the destructor (a few times in a row). Again I'm very puzzeled. After converting again from char* to Cstring and back and forth it stops. It never get's into the = operator but neither does it go further. printf(a) is never reached. I use VisualStudio 2010 for this but it's basically just standard c++ code and thus I don't think it should make that much of a difference

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  • Issue reading in a cell from Excel with Apache POI

    - by Nick
    I am trying to use Apache POI to read in old (pre-2007 and XLS) Excel files. My program goes to the end of the rows and iterates back up until it finds something that's not either null or empty. Then it iterates back up a few times and grabs those cells. This program works just fine reading in XLSX and XLS files made in Office 2010. I get the following error message: Exception in thread "main" java.lang.NumberFormatException: empty String at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source) at java.lang.Double.parseDouble(Unknown Source) at the line: num = Double.parseDouble(str); from the code: str = cell.toString(); if (str != "" || str != null) { System.out.println("Cell is a string"); num = Double.parseDouble(str); } else { System.out.println("Cell is numeric."); num = cell.getNumericCellValue(); } where the cell is the last cell in the document that's not empty or null. When I try to print the first cell that's not empty or null, it prints nothing, so I think I'm not accessing it correctly.

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  • can I acces a struct inside of a struct without using the dot operator?

    - by yan bellavance
    I have 2 structures that have 90% of their fields the same. I want to group those fields in a structure but I do not want to use the dot operator to access them. The reason is I already coded with the first structure and have just created the second one. before: struct{ int a; int b; int c; object1 name; }str1; struct{ int a; int b; int c; object2 name; }str2; now I would create a third struct: struct{ int a; int b; int c; }str3; and would change the str1 and atr2 to this: struct{ str3 str; object1 name; }str1; struct { str3 str; object2 name; }str2; Finally I would like to be able to access a,b and c by doing: str1 myStruct; myStruct.a; myStruct.b; myStruct.c; and not: myStruct.str.a; myStruct.str.b; myStruct.str.c; Is there a way to do such a thing. The reason for doing this is I want keep the integrety of the data if chnges to the struct were to occur and to not repeat myself and not have to change my existing code and not have fields nested too deeply.

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  • template class: ctor against function -> new C++ standard

    - by Oops
    Hi in this question: http://stackoverflow.com/questions/2779155/template-point2-double-point3-double Dennis and Michael noticed the unreasonable foolishly implemented constructor. They were right, I didn't consider this at that moment. But I found out that a constructor does not help very much for a template class like this one, instead a function is here much more convenient and safe namespace point { template < unsigned int dims, typename T > struct Point { T X[ dims ]; std::string str() { std::stringstream s; s << "{"; for ( int i = 0; i < dims; ++i ) { s << " X" << i << ": " << X[ i ] << (( i < dims -1 )? " |": " "); } s << "}"; return s.str(); } Point<dims, int> toint() { Point<dims, int> ret; std::copy( X, X+dims, ret.X ); return ret; } }; template < typename T > Point< 2, T > Create( T X0, T X1 ) { Point< 2, T > ret; ret.X[ 0 ] = X0; ret.X[ 1 ] = X1; return ret; } template < typename T > Point< 3, T > Create( T X0, T X1, T X2 ) { Point< 3, T > ret; ret.X[ 0 ] = X0; ret.X[ 1 ] = X1; ret.X[ 2 ] = X2; return ret; } template < typename T > Point< 4, T > Create( T X0, T X1, T X2, T X3 ) { Point< 4, T > ret; ret.X[ 0 ] = X0; ret.X[ 1 ] = X1; ret.X[ 2 ] = X2; ret.X[ 3 ] = X3; return ret; } }; int main( void ) { using namespace point; Point< 2, double > p2d = point::Create( 12.3, 34.5 ); Point< 3, double > p3d = point::Create( 12.3, 34.5, 56.7 ); Point< 4, double > p4d = point::Create( 12.3, 34.5, 56.7, 78.9 ); //Point< 3, double > p1d = point::Create( 12.3, 34.5 ); //no suitable user defined conversion exists //Point< 3, int > p1i = p4d.toint(); //no suitable user defined conversion exists Point< 2, int > p2i = p2d.toint(); Point< 3, int > p3i = p3d.toint(); Point< 4, int > p4i = p4d.toint(); std::cout << p2d.str() << std::endl; std::cout << p3d.str() << std::endl; std::cout << p4d.str() << std::endl; std::cout << p2i.str() << std::endl; std::cout << p3i.str() << std::endl; std::cout << p4i.str() << std::endl; char c; std::cin >> c; } has the new C++ standard any new improvements, language features or simplifications regarding this aspect of ctor of a template class? what do you think about the implementation of the combination of namespace, stuct and Create function? many thanks in advance Oops

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  • Exporting dates properly formatted on Google Appengine in Python

    - by Chris M
    I think this is right but google appengine seems to get to a certain point and cop-out; Firstly is this code actually right; and secondly is there away to skip the record if it cant output (like an ignore errors and continue)? class TrackerExporter(bulkloader.Exporter): def __init__(self): bulkloader.Exporter.__init__(self, 'SearchRec', [('__key__', lambda key:key.name(), None), ('WebSite', str, None), ('DateStamp', lambda x: datetime.datetime.strptime(x, '%d-%m-%Y').date(), None), ('IP', str, None), ('UserAgent', str, None)]) Thanks

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