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  • [C]Dynamic allocation memory of structure, related to GTK

    - by MakeItWork
    Hello, I have following structure: typedef struct { GtkWidget* PoziomaLinijka; GtkWidget* PionowaLinijka; GtkWidget* Label1; GtkWidget* Label2; gint x,y; } StrukturaDrawing; And i need to allocate it on the heap because later I have functions which uses that structure and I don't want to use global variables. So I allocate it like this: StrukturaDrawing* Wsk; Wsk = (StrukturaDrawing*)malloc(sizeof(StrukturaDrawing)); if (!Wsk) { printf("Error\n"); } And it doesn't returning error and also works great with other functions, it works the way I wanted it to work so finally i wanted to free that memory and here is problem because in Debug Mode compilator bitches: First-chance exception at 0x102d12b4 in GTK.exe: 0xC0000005: Access violation reading location 0xfffffffc. Unhandled exception at 0x102d12b4 in GTK.exe: 0xC0000005: Access violation reading location 0xfffffffc. I connect callback to my function, like that: g_signal_connect(G_OBJECT(Okno), "destroy", G_CALLBACK(Wyjscie), Wsk); Function which is suppose to free memory and close program: void Wyjscie(GtkWindow* window, GdkEvent* event, StrukturaDrawing* data) { gtk_main_quit(); free(data); data = NULL; } Any help really appreciated.

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  • Why does the order of the loops affect performance when iterating over a 2D array? [closed]

    - by Mark
    Possible Duplicate: Which of these two for loops is more efficient in terms of time and cache performance Below are two programs that are almost identical except that I switched the i and j variables around. They both run in different amounts of time. Could someone explain why this happens? Version 1 #include <stdio.h> #include <stdlib.h> main () { int i,j; static int x[4000][4000]; for (i = 0; i < 4000; i++) { for (j = 0; j < 4000; j++) { x[j][i] = i + j; } } } Version 2 #include <stdio.h> #include <stdlib.h> main () { int i,j; static int x[4000][4000]; for (j = 0; j < 4000; j++) { for (i = 0; i < 4000; i++) { x[j][i] = i + j; } } }

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  • fgets throwing unhandled exception while parsing stl

    - by user3478400
    I am new to c++, I am trying to parse a stl file which is of about 64MB and has about ~18K lines in it. The code works fine for first few 100 lines but then fgets throws following exception: "Unhandled exception at 0x77B0BAC5 (ntdll.dll) in STLparser.exe: 0xC0000024: There is a mismatch between the type of object required by the requested operation and the type of object that is specified in the request." I have checked manually the line for which fgets throws exception, there is nothing out of ordinary there. I am out of options for now. Any help to fix this issue will be greatly appreciated. ================CODE========================== #include<fstream> #include<iostream> #include"ParseString.h" #include"Vectors.h" using namespace std; int main(void) { //Define variables FILE *file; char *line = new char; parsestring oneline; int n_Vols = 0, n_Elms = 0, n_nods = -1, E = 0; Nod *nodes = new Nod(); Nod dummy; Elm *elements = new Elm(); int mycounter = 0; //Open file fopen_s(&file, "sample.stl", "r"); while (fgets(line, 1024, file) != NULL) //**********Getting Error Here************* { // populate required data } fclose(file); printf("%d,%d,%d", n_Vols, n_Elms, n_nods); getchar(); return 0; } ===================When broken, execution resumes at this function (not my function, something internal) void __cdecl _unlock ( int locknum ) { /* * leave the critical section. */ LeaveCriticalSection( _locktable[locknum].lock ); }

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  • How is this function being made use of?

    - by Kay
    Hello all, I am just studying a few classes given to me by my lecturer and I can't understand how the function heapRebuild is being made used of! It doesn't change any global variables and it doesn't print out anything ad it doesn't return anything - so should this even work? It shouldn't, should it? If you were told to make use of heapRebuild to make a new function removeMac would you edit heapRebuild? public class MaxHeap<T extends Comparable<T>> implements Heap<T>{ private T[] heap; private int lastIndex; public T removeMax(){ T rootItem = heap[0]; heap[0] = heap[lastIndex-1]; lastIndex--; heapRebuild(heap, 0, lastIndex); return rootItem; } protected void heapRebuild(T[ ] items, int root, int size){ int child = 2*root+1; if( child < size){ int rightChild = child+1; if ((rightChild < size) && (items[rightChild].compareTo(items[child]) > 0)){ child = rightChild; } if (items[root].compareTo(items[child]) < 0){ T temp = items[root]; items[root] = items[child]; items[child] = temp; heapRebuild(items, child, size);} } } }

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  • excel:mysql: rs.Update not working

    - by every_answer_gets_a_point
    i am updating a table using an ODBC connection from excel to mysql unfortunately the only column that gets updated is this one: .Fields("instrument") = "NA" where i am assigning variables to .Fields, it is putting NULL values!! what is going on here? here's the code Option Explicit Dim oConn As ADODB.Connection Private Sub ConnectDB() Set oConn = New ADODB.Connection oConn.Open "DRIVER={MySQL ODBC 5.1 Driver};" & _ "SERVER=localhost;" & _ "DATABASE=employees;" & _ "USER=root;" & _ "PASSWORD=pas;" & _ "Option=3" End Sub Function esc(txt As String) esc = Trim(Replace(txt, "'", "\'")) End Function Private Sub InsertData() Dim dpath, atime, rtime, lcalib, aname, rname, bstate, instrument As String Dim rs As ADODB.Recordset Set rs = New ADODB.Recordset ConnectDB With wsBooks rs.Open "batchinfo", oConn, adOpenKeyset, adLockOptimistic, adCmdTable Worksheets.Item("Report 1").Select dpath = Trim(Range("B2").Text) atime = Trim(Range("B3").Text) rtime = Trim(Range("B4").Text) lcalib = Trim(Range("B5").Text) aname = Trim(Range("B6").Text) rname = Trim(Range("B7").Text) bstate = Trim(Range("B8").Text) ' instrument = GetInstrFromXML(wbBook.FullName) With rs .AddNew ' create a new record ' add values to each field in the record .Fields("datapath") = dpath .Fields("analysistime") = atime .Fields("reporttime") = rtime .Fields("lastcalib") = lcalib .Fields("analystname") = aname .Fields("reportname") = rname .Fields("batchstate") = bstate .Fields("instrument") = "NA" .Update ' stores the new record End With ' get the last id Set rs = oConn.Execute("SELECT @@identity", , adCmdText) 'MsgBox capture_id rs.Close Set rs = Nothing End With End Sub

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  • OutOfMemoryError creating a tree recursively?

    - by Alexander Khaos Greenstein
    root = new TreeNode(N); constructTree(N, root); private void constructTree(int N, TreeNode node) { if (N > 0) { node.setLeft(new TreeNode(N-1)); constructTree(N-1, node.getLeft()); } if (N > 1) { node.setMiddle(new TreeNode(N-2)); constructTree(N-2, node.getMiddle()); } if (N > 2) { node.setRight(new TreeNode(N-3)); constructTree(N-3, node.getRight()); } Assume N is the root number, and the three will create a left middle right node of N-1, N-2, N-3. EX: 5 / | \ 4 3 2 /|\ 3 2 1 etc. My GameNode class has the following variables: private int number; private GameNode left, middle, right; Whenever I construct a tree with an integer greater than 28, I get a OutOfMemoryError. Is my recursive method just incredibly inefficient or is this natural? Thanks!

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  • Variable from block is put into a calculation but throws off wrong reading

    - by user2926620
    I am having troubles with trying to retrieve a double variable that is already established outside the block and called inside but I want to return the value of the same variable so that I can apply it to a calculation. the variable that I want returned is: double quarter = 0; but when I plug it into quarter in my first else/if statement, it plugs in 0 and not the value in my switch block. What can I do to retrieve the value? double quarter = 0; //Date entry will be calculated by how much KW user enters switch (input) { case "2/15/13": quarter = kwUsed * 0.10; break; case "4/15/13": quarter = kwUsed * 0.12; break; case "8/15/13": quarter = kwUsed * 0.15; break; case "11/15/13": quarter = kwUsed * 0.15; break; default: System.out.println("Invalid date"); } //Declaring variables for calculations double base = 0; double over = 0; double excess = 0; double math1 = 0; double math2 = 0; //KW Calculations if (kwUsed <= 350) { base = quarter; }else if (kwUsed <= 500) { math1 = ((kwUsed - 350) * quarter); base = ((kwUsed * quarter) - math1); over = ((math1 * 0.1) + math1); }else if (kwUsed > 500) { math2 = ((kwUsed - 350) * 0.1); base = ((kwUsed * 0.1) - math2); math2 = ((kwUsed -350) - 50); over = ((math2 * 0.1) + (15 * 0.1)); double math3 =((kwUsed - 500) * 0.1); excess = ((math3 * 0.25) + math3); } Edited to clarify question.

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  • Questions about shifting from mysql to PDO

    - by Scarface
    Hey guys I have recently decided to switch all my current plain mysql queries performed with php mysql_query to PDO style queries to improve performance, portability and security. I just have some quick questions for any experts in this database interaction tool Will it prevent injection if all statements are prepared? (I noticed on php.net it wrote 'however, if other portions of the query are being built up with unescaped input, SQL injection is still possible' I was not exactly sure what this meant). Does this just mean that if all variables are run through a prepare function it is safe, and if some are directly inserted then it is not? Currently I have a connection at the top of my page and queries performed during the rest of the page. I took a look at PDO in more detail and noticed that there is a try and catch procedure for every query involving a connection and the closing of that connection. Is there a straightforward way to connecting and then reusing that connection without having to put everything in a try or constantly repeat the procedure by connecting, querying and closing? Can anyone briefly explain in layman's terms what purpose a set_exception_handler serves? I appreciate any advice from any more experienced individuals.

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  • How should I solve this MySql problem (PHP) ? (Beginner)

    - by Camran
    I have several tables in a MySql database. I have a classifieds website, and at the bottom I display the users last visited classifieds. I do this by storing the ID:s of the ads to an array in the cookie. Now, my db is made up like this kindof: Main Table: // Stores global information, ie these fields have to be filled out in every record, never be blank ID Price category Seller Item Table: // Stores descriptive info about whats for sale ID AD_ID (FK) //This is the same as ID in the MAIN TABLE Color Size Mileage etc My problem is that I need to know what category the ad is in, in order to query mysql for the right information I think. So I need two variables, but the cookie only has one (ID) stored. Offcourse I could make two queries, first one just matching the ID to the main_table and fetch the category from the Main_table. Then make the second query and fetch all other info from the right table. Here is an example if the category was Vehicles: SELECT * FROM main_table, vehicles_table, WHERE main_table.id=$id_from_cookie AND main_table.ad_id=vehicles_table.ad_id As you can see above, I need the category to write in what table to check, right? But I think there must be a smarter way, like fetching them in one single query using only one variable (id from cookie)? How should I do this? Understand? Let me know if you need more input... Thanks

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  • Assigning values from list to list excluding nulls

    - by GutierrezDev
    Hi. Sorry for the title but I don't know other way of asking. I got 2 Dictionary < string,string list One of them has a length of 606 items including null values. The other one has a length of 285 items. I determined the length doing this: int count = 0; for (int i = 0; i < temp.Length; i++) { if (temp[i] != null) count++; } Now I want to assign every value in the temp variable to another variable excluding the null values. Any Idea? Remember that I have a different size variables. Edited Dictionary<string, string>[] info; Dictionary<string, string>[] temp = new Dictionary<string, string>[ds.Tables[0].Rows.Count]; .... Here I added some data to the Temp variable ..... Then this: int count = 0 for (int i = 0; i < temp.Length; i++) { if (temp[i] != null) count++; } info = new Dictionary<string, string>[count]; Hope you understand now.

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  • Error : 'java' is not recognized as an internal or external command, operable program or batch file.

    - by Setu
    I have my application online on the Google Apps Engine. When I deploy this application, this error is generated. I am using Netbeans 6.9. My jdk is installed at : "C:\Program Files\Java\jdk1.6.0_23\". I have installed Google App Engine for Java. This application is getting deployed & run on localhost very well. I am also able to start Google App Engine Server. I have set Environment variables as : 1) classpath : C:\Program Files\Java\jdk1.6.0_23\bin; 2) path : C:\Program Files\Java\jdk1.6.0_23\bin; 3) JAVA_HOME : C:\Program Files\Java\jdk1.6.0_23\bin; 4) include : C:\Program Files\Java\jdk1.6.0_23\include; 5) lib : C:\Program Files\Java\jdk1.6.0_23\lib; However, in system32, I am not finding java.exe, javac.exe or javawc.exe. Also, while running this : 1) java.exe 2) javac.exe 3) java -version from Command Line, they give proper output. How do I make my application properly deployed ?

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  • table in drupal with edit link

    - by user544079
    I have a table created in drupal with the edit link pointing to the input form. But the problem is, it only displays the last row values in the $email and $comment variables. Can anyone suggest how to modify the table display to have the edit link to the corresponding records? function _MYMODULE_sql_to_table($sql) { $html = ""; // execute sql $resource = db_query($sql); // fetch database results in an array $results = array(); while ($row = db_fetch_array($resource)) { $results[] = $row; $email = $row['email']; $comment = $row['comment']; drupal_set_message('Email: '.$email. ' comment: '.$comment); } // ensure results exist if (!count($results)) { $html .= "Sorry, no results could be found."; return $html; } // create an array to contain all table rows $rows = array(); // get a list of column headers $columnNames = array_keys($results[0]); // loop through results and create table rows foreach ($results as $key => $data) { // create row data $row = array( 'edit' => l(t('Edit'),"admin/content/test/$email/$comment/ContactUs", $options=array()),); // loop through column names foreach ($columnNames as $c) { $row[] = array( 'data' => $data[$c], 'class' => strtolower(str_replace(' ', '-', $c)), ); } // add row to rows array $rows[] = $row; } // loop through column names and create headers $header = array(); foreach ($columnNames as $c) { $header[] = array( 'data' = $c, 'class' = strtolower(str_replace(' ', '-', $c)), ); } // generate table html $html .= theme('table', $header, $rows); return $html; } // then you can call it in your code... function _MYMODULE_some_page_callback() { $html = ""; $sql = "select * from {contactus}"; $html .= _MYMODULE_sql_to_table($sql); return $html; }

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  • Inheritance not working

    - by Pendo826
    Hey im just practicing inheritance and i encountered a problem. Im getting an error in my car class(sub-class) that the variables in Vehicle(parent) are not visible. i didnt do anything to change this and i dont even know how to make it invisible. Can anyone help me with this. public class Vehicle { private String make, model, colour; private int registrationNumber; public Vehicle() { this.make = ""; this.model = ""; this.colour = ""; this.registrationNumber = 0; } public Vehicle(String make, String model, String colour, int registrationNumber) { this.make = make; this.model = model; this.colour = colour; this.registrationNumber = registrationNumber; } public String getMake() { return make; } public void setMake(String make) { this.make = make; } public String getModel() { return model; } public void setModel(String model) { this.model = model; } public String getColour() { return colour; } public void setColour(String colour) { this.colour = colour; } public int getRegistrationNumber() { return registrationNumber; } public void setRegistrationNumber(int registrationNumber) { this.registrationNumber = registrationNumber; } public String toString() { return "Vehicle [make=" + make + ", model=" + model + ", colour=" + colour + ", registrationNumber=" + registrationNumber + "]"; } } public Car() { super(); this.doors = 0; this.shape = ""; } public Car(int doors, String shape, String make, String model, String colour, int registrationNumber) { super(); this.doors = doors; this.shape = shape; this.make = make;//Error this.model = model;//Error this.colour = colour;//Error this.registrationNumber = registrationNumber;//Error } The error message: Description Resource Path Location Type The field Vehicle.make is not visible Car.java /VehicleApp/src line 19 Java Problem The field Vehicle.model is not visible Car.java /VehicleApp/src line 20 Java Problem The field Vehicle.colour is not visible Car.java /VehicleApp/src line 21 Java Problem The field Vehicle.registrationNumber is not visible Car.java /VehicleApp/src line 22 Java Problem

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  • jQuery variable and object caching

    - by niksy
    This is something that has been bugging me some time and every time I found myself using different solution for this. So, I have link in my document which on click creates new element with some ID. <a href="#" id="test-link">Link</a> For the purpose of easier reusing, I would like to store that new elements ID in a variable which is jQuery object var test = $('#test'); On click I append that new element on body, new element is DIV $('body').append('<div id="test"/>'); And here goes the main "problem" - if I test this new elements length with test.length it first returns 0 and later 1. But, when I test it with $('#test').length it returns 1 from the start. I suppose it is some caching mechanism and I was wondering is there better, all-around solution which will allow to store elements in variables in the start for later repurpose and in the same time work with dynamically created elements. Live, delegate, something else? What I do sometimes is create string and add it to jQuery object but I think this is just avoiding the real issue. Also, using .find() inside another jQuery object. Thanks in advance.

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  • set countdown correctly, as3

    - by VideoDnd
    How can I set my countdown correctly? I'm counting from 33,000.00 to zero. It works in a fashion, but the minus operator appears in the textfield. //Countdown from 33,000.00 to zero var timer:Timer = new Timer(10); var count:int = -3300000; var fcount:int = 0; timer.addEventListener(TimerEvent.TIMER, incrementCounter); timer.start(); function incrementCounter(event:TimerEvent) { count++; fcount=int(count); mytext.text = formatCount(fcount); } function formatCount(i:int):String { var fraction:int = i % 100; var whole:int = i / 100; return ("0000000" + whole).substr(-7, 7) + "." + (fraction < 10 ? "0" + fraction : fraction); } EXAMPLE I need something I can update with XML, to be an up-counter or down-counter depending on the variables. //Count up from 33,000.00 var countValue:int = 3300000; count = countValue; //Count down from 33,000.00 var countValue:int = -3300000; count = countValue;

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  • PHP: Trying to come up with a "prev" and "next" link

    - by fwaokda
    I'm displaying 10 records per page. The variables I have currently that I'm working with are.. $total = total number of records $page = whats the current page I'm displaying I placed this at the top of my page... if ( $_GET['page'] == '' ) { $page = 1; } //if no page is specified set it to `1` else { $page = ($_GET['page']); } // if page is specified set it Here are my two links... if ( $page != 1 ) { echo '<div style="float:left" ><a href="index.php?page='. ( $page - 1 ) .'" rev="prev" >Prev</a></div>'; } if ( !( ( $total / ( 10 * $page ) ) < $page ) ) { echo '<div style="float:right" ><a href="index.php?page='. ( $page + 1 ) .'" rev="next" >Next</a></div>'; } Now I guess (unless I'm not thinking of something) that I can display the "Prev" link every time except when the page is '1'. How can make it where the "Next" link doesn't show on the last page though?

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  • Main purpose of this task is to calculate volumes and surface areas of three dimensional geometric shapes like, cylinders, cones.

    - by Csc_Girl_Geek
    In Java Language Design your classes as below introducing: an Interface named “GeometricShapes” an abstract class named “ThreeDShapes” two child classes of ThreeDShapes: Cylinders and Cones. One test class names “TestShapes” Get the output for volumes and surface areas of cylinders and cones along with respective values of their appropriate input variables. Try to use toString() method and array. Your classes should be designed with methods that are required for Object-Oriented programming. So Far I Have: package Assignment2; public interface GeometricShapes { public void render(); public int[] getPosition(); public void setPosition(int x, int y); } package Assignment2; public abstract class ThreeDShapes implements GeometricShapes { public int[] position; public int[] size; public ThreeDShapes() { } public int[] getPosition() { return position; } public void setPosition(int x, int y) { position[0] = x; position[1] = y; } } package Assignment2; public class Cylinders extends ThreeDShapes { public Cylinder() { } public void render() { } } I don't think this is right and I do not know how to fix it. :( Please help.

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  • problem using fprintf

    - by shiran bar
    I'm trying to print to a text file numerous variables yet it doesn't work. I checked and verified that i write it in the correct syntax. I also checked the return value and it's positive therefore i know it did write to the file, however when i open the file it's empty. I would be happy for some help. This is the code: I initiate DynsaleDayPtr in the main: FILE* DynsaleDayPtr = CreateTextFiles("sale_day.txt"); Create function: FILE* CreateTextFiles (char* fileName) { FILE* saleFilePtr=NULL; if((saleFilePtr=fopen(fileName,"a+"))==NULL) printf("File couldn't be opened\n"); return saleFilePtr; } The call to the function TextAddSale is done from a function that is called in the main: TextAddSale(DynSaleDayPtr,dynNumOfRecords); Bool TextAddSale (FILE* DynsaleDayPtr, int* dynNumOfRecords) { char id[6]; char name [50]; char priceChar[20]; char* tmp = NULL; int price=-1; DynamicRecord * newRec=NULL; scanf("%s%s%s",id,name,priceChar); newRec = (DynamicRecord *)malloc(sizeof(DynamicRecord)); if (newRec == NULL) return False; tmp = (char*)malloc(strlen(name)+1); if (tmp == NULL) { free (newRec); return False; } strcpy(tmp,name); newRec->productName = tmp; strcpy(newRec->productId, id); newRec->productPrice=atoi (priceChar); if (fprintf(DynsaleDayPtr,"%d %s %s %d", strlen(newRec->productName), newRec->productId, newRec->productName, newRec->productPrice)>0) { *dynNumOfRecords=(*dynNumOfRecords)+1; return True; } } thanks!

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  • Which way of declaring a variable is fastest?

    - by ADB
    For a variable used in a function that is called very often and for implementation in J2ME on a blackberry (if that changed something, can you explain)? class X { int i; public void someFunc(int j) { i = 0; while( i < j ){ [...] i++; } } } or class X { static int i; public void someFunc(int j) { i = 0; while( i < j ){ [...] i++; } } } or class X { public void someFunc(int j) { int i = 0; while( i < j ){ [...] i++; } } } I know there is a difference how a static versus non-static class variable is accessed, but I don't know it would affect the speed. I also remember reading somewhere that in-function variables may be accessed faster, but I don't know why and where I read that. Background on the question: some painting function in games are called excessively often and even small difference in access time can affect the overall performance when a variable is used in a largish loop.

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  • has_many through and saving to join table

    - by Paul
    I have the following: class Invite < ActiveRecord::Base belongs_to :user has_many :invite_recipients has_many :recipients, :through => :invite_recipients end class InviteRecipient < ActiveRecord::Base belongs_to :invite belongs_to :user_comm validates_associated :user_comm, :invite validates_uniqueness_of :user_comm_id, :scope => :invite_id end class UserComm < ActiveRecord::Base end I'd like to create a method for Invite with invite_text and a list of UserComms as the variables and then have it create a new invite with the following validations: 1. All UserComms are unique 2. The invite isn't saved unless all the associated InviteRecipients are saved as well (in other words, the invite isn't valid unless all the created InviteRecipients are valid) I'm not familiar with how to create model functions. Moreover, when I try something like this: i = Invite.new(:invite_text => 'come join') ir1 = InviteRecipient.new(:invite => i, :user_comm => user_comm1) ir2 = InviteRecipient.new(:invite => i, :user_comm => user_comm2) i.invite_recipients = [uc1, uc2] i.save! I get: SystemStackError: stack level too deep

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  • Trouble understanding the semantics of volatile in Java

    - by HungryTux
    I've been reading up about the use of volatile variables in Java. I understand that they ensure instant visibility of their latest updates to all the threads running in the system on different cores/processors. However no atomicity of the operations that caused these updates is ensured. I see the following literature being used frequently A write to a volatile field happens-before every read of that same field . This is where I am a little confused. Here's a snippet of code which should help me better explain my query. volatile int x = 0; volatile int y = 0; Thread-0: | Thread-1: | if (x==1) { | if (y==1) { return false; | return false; } else { | } else { y=1; | x=1; return true; | return true; } | } Since x & y are both volatile, we have the following happens-before edges between the write of y in Thread-0 and read of y in Thread-1 between the write of x in Thread-1 and read of x in Thread-0 Does this imply that, at any point of time, only one of the threads can be in its 'else' block(since a write would happen before the read)? It may well be possible that Thread-0 starts, loads x, finds it value as 0 and right before it is about to write y in the else-block, there's a context switch to Thread-1 which loads y finds it value as 0 and thus enters the else-block too. Does volatile guard against such context switches (seems very unlikely)?

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  • What's an effective way to reuse ArrayLists in a for loop?

    - by Patrick
    hi, I'm reusing the same ArrayList in a for loop, and I use for loop results = new ArrayList<Integer>(); experts = new ArrayList<Integer>(); output = new ArrayList<String>(); .... to create new ones. I guess this is wrong, because I'm allocating new memory. Is this correct ? If yes, how can I empty them ? Added: another example I'm creating new variables each time I call this method. Is this good practice ? I mean to create new precision, relevantFound.. etc ? Or should I declare them in my class, outside the method to not allocate more and more memory ? public static void computeMAP(ArrayList<Integer> results, ArrayList<Integer> experts) { //compute MAP double precision = 0; int relevantFound = 0; double sumprecision = 0; thanks

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  • Why is this giving me an infinite loop?

    - by Chase Yuan
    I was going through a code used to calculate investments until it has doubled and I received an infinite loop that I can't seem to solve. Can anyone figure out why this is giving me an infinite loop? I've gone through myself but I can't seem to find the problem. The "period" referred is how many times per year the interest is compounded. double account = 0; //declares the variables to be used double base = 0; double interest = 0; double rate = 0; double result = 0; double times = 0; int years = 0; int j; System.out.println("This is a program that calculates interest."); Scanner kbReader = new Scanner(System.in); //enters in all data System.out.print("Enter account balance: "); account = kbReader.nextDouble(); System.out.print("Enter interest rate (as decimal): "); rate = kbReader.nextDouble(); System.out.println(" " + "Years to double" + " " + "Ending balance"); base = account; result = account; for (j=0; j<3; j++){ System.out.print("Enter period: "); times = kbReader.nextDouble(); while (account < base*2){ interest = account * rate / times; account = interest + base; years++; } account = (((int)(account * 100))/100.0); //results System.out.print(" " + i + " " + account + "\n"); account = result; } The code should ask for three "periods", or three different times the entered data is compounded per year (ex annually, monthly, daily etc.) Thanks a lot!

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  • Why does this sql statement keep saying it is a boolean and not a parameter? (php/Mysql)

    - by ggfan
    In this statement, I am trying to see if there if the latest posting in the database that has the exact same title, price, city, state, detail. If there is, then it would say to the user that the exact post has been already made; if not then insert the posting into the dbc. (This is one type of check so that users can't accidentally post twice. This may not be the best check, but this statement error is annoying me, so I want it to work :)) Why won't this sql work? I think it's not letting the title=$title and not getting the value in the $title... ERROR: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in postad.php on line 365 //there is a form that users fill out that has title, price, city, etc <form> blah blah </form> //if users click submit, then does all the checks and if all okay, insert to dbc if (isset($_POST['submit'])) { // Grab the pposting data from the POST and gets rid of any funny stuff $title = mysqli_real_escape_string($dbc, trim($_POST['title'])); $price = mysqli_real_escape_string($dbc, trim($_POST['price'])); $city = mysqli_real_escape_string($dbc, trim($_POST['city'])); $state = mysqli_real_escape_string($dbc, trim($_POST['state'])); $detail = mysqli_real_escape_string($dbc, trim($_POST['detail'])); if (!is_numeric($price) && !empty($price)) { echo "<p class='error'>The price can only be numbers. No special characters, etc</p>"; } //Error problem...won't let me set title=$title, detail=$detail, etc. //this statement after all the checks so that none of the variables are empty $query="Select * FROM posting WHERE user_id={$_SESSION['user_id']} AND title=$title AND price=$price AND city=$city AND state=$state AND detail=$detail"; $data = mysqli_query($dbc, $query); if(mysqli_num_rows($data)==1) { echo "You already posted this ad. Most likely caused by refreshing too many times."; } }

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  • Dynamic programming Approach- Knapsack Puzzle

    - by idalsin
    I'm trying to solve the Knapsack problem with the dynamical programming(DP) approach, with Python 3.x. My TA pointed us towards this code for a head start. I've tried to implement it, as below: def take_input(infile): f_open = open(infile, 'r') lines = [] for line in f_open: lines.append(line.strip()) f_open.close() return lines def create_list(jewel_lines): #turns the jewels into a list of lists jewels_list = [] for x in jewel_lines: weight = x.split()[0] value = x.split()[1] jewels_list.append((int(value), int(weight))) jewels_list = sorted(jewels_list, key = lambda x : (-x[0], x[1])) return jewels_list def dynamic_grab(items, max_weight): table = [[0 for weight in range(max_weight+1)] for j in range(len(items)+1)] for j in range(1,len(items)+1): val= items[j-1][0] wt= items[j-1][1] for weight in range(1, max_weight+1): if wt > weight: table[j][weight] = table[j-1][weight] else: table[j][weight] = max(table[j-1][weight],table[j-1][weight-wt] + val) result = [] weight = max_weight for j in range(len(items),0,-1): was_added = table[j][weight] != table[j-1][weight] if was_added: val = items[j-1][0] wt = items[j-1][1] result.append(items[j-1]) weight -= wt return result def totalvalue(comb): #total of a combo of items totwt = totval = 0 for val, wt in comb: totwt += wt totval += val return (totval, -totwt) if totwt <= max_weight else (0,0) #required setup of variables infile = "JT_test1.txt" given_input = take_input(infile) max_weight = int(given_input[0]) given_input.pop(0) jewels_list = create_list(given_input) #test lines print(jewels_list) print(greedy_grab(jewels_list, max_weight)) bagged = dynamic_grab(jewels_list, max_weight) print(totalvalue(bagged)) The sample case is below. It is in the format line[0] = bag_max, line[1:] is in form(weight, value): 575 125 3000 50 100 500 6000 25 30 I'm confused as to the logic of this code in that it returns me a tuple and I'm not sure what the output tuple represents. I've been looking at this for a while and just don't understand what the code is pointing me at. Any help would be appreciated.

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