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• Problem using a COM interface as parameter

  - by Cesar

  I have the following problem: I have to projects Project1 and Project2. In Project1 I have an interface IMyInterface. In Project2 I have an interface IMyInterface2 with a method that receives a pointer to IMyInterface1. When I use import "Project1.idl"; in my Project2.idl, a #include "Project1.h" appears in Project2___i.h. But this file does not even exist!. What is the proper way to import an interface defined into other library into a idl file? I tried to replace the #include "Project1.h" by *#include "Project1_i.h"* or *#include "Project1_i.c"*, but it gave me a lot of errors. I also tried to use importlib("Project1.tlb") and define my interface IMyInterface2 within the library definition. But when I compile Project2PS project, an error is raised (something like dlldata.c is not generated if no interface is defined). I tried to create a dummy Project1.h. But when Project2___i.h is compiled, compiler cannot find MyInterface1. And if I include Project1___i.h I get a lot of errors again! Apparently, it is a simple issue, but I don't know how to solve it. I'm stuck with that!. By the way, I'm using VS2008 SP1. Thanks in advance.

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• How can multiple variables be passed to a function cleanly in C?

  - by aquanar

  I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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• [FIXED] Scan file contents into an array of a structure.

  - by ZaZu

  Hello, I have a structure in my program that contains a particular array. I want to scan a random file with numbers and put the contents into that array. This is my code : ( NOTE : This is a sample from a bigger program, so I need the structure and arrays as declared ) The contents of the file are basically : 5 4 3 2 5 3 4 2 #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; FILE *fin; fin=fopen("randomfile.txt","r"); for(i=0;i<5;i++){ fscanf(fin,"%5.2f\t",(*test).what[z][x]); } fclose(fin); return 0; } But the problem is, whenever this I run this code, I get this error : (25) : warning 508 - Data of type 'double' supplied where a pointer is required I tried adding do{ for(i=0;i<5;i++){ q=fscanf(fin,"%5.2f\t",(*test).what[z][x]); } }while(q!=EOF); But that didnt work either, it gives the same error. Does anyone have a solution to this problem ?

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• How to cast C struct just another struct type if their memory size are equal?

  - by Eonil

  I have 2 matrix structs means equal data but have different form like these: // Matrix type 1. typedef float Scalar; typedef struct { Scalar e[4]; } Vector; typedef struct { Vector e[4]; } Matrix; // Matrix type 2 (you may know this if you're iPhone developer) struct CATransform3D { CGFloat m11, m12, m13, m14; CGFloat m21, m22, m23, m24; CGFloat m31, m32, m33, m34; CGFloat m41, m42, m43, m44; }; typedef struct CATransform3D CATransform3D; Their memory size are equal. So I believe there is a way to convert these types without any pointer operations or copy like this: // Implemented from external lib. CATransform3D CATransform3DMakeScale (CGFloat sx, CGFloat sy, CGFloat sz); Matrix m = (Matrix)CATransform3DMakeScale ( 1, 2, 3 ); Is this possible? Currently compiler prints an "error: conversion to non-scalar type requested" message.

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• C struct written in file, open with Java

  - by DaunnC

  For example in C I have structure: typedef struct { int number; double x1; double y1; double x2; double y2; double x3; double y3; } CTRstruct;` Then I write it to file fwrite(&tr, 1, sizeof(tr), fp); (tr - its CTRstruct var, fp - File pointer); Then I need to read it with Java! I really don't know how to read struct from file... I tried to read it with ObjectInputStream(), last idea is to read with RandomAccessFile() but I also don't know how to... (readLong(), readDouble() also doesn't work, it works ofcource but doesn't read correct data). So, any idea how to read C struct from binary file with Java? If it's interesting, my version to read integer (but it's ugly, & I don't know what to do with double): public class MyDataInputStream extends DataInputStream{ public MyDataInputStream(InputStream AIs) { super(AIs); } public int readInt1() throws IOException{ int ch1 = in.read(); int ch2 = in.read(); int ch3 = in.read(); int ch4 = in.read(); if ((ch1 | ch2 | ch3 | ch4) < 0) throw new EOFException(); return ((ch4 << 24) + (ch3 << 16) + (ch2 << 8) + (ch1 << 0)); } with double we can deal the same way (like with int or with long (8bytes) & then convert to double with native func).

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• Advice: Python Framework Server/Worker Queue management (not Website)

  - by Muppet Geoff

  I am looking for some advice/opinions of which Python Framework to use in an implementation of multiple 'Worker' PCs co-ordinated from a central Queue Manager. For completeness, the 'Worker' PCs will be running Audio Conversion routines (which I do not need advice on, and have standalone code that works). The Audio conversion takes a long time, and I need to co-ordinate an arbitrary number of the 'Workers' from a central location, handing them conversion tasks (such as where to get the source files, or where to ask for the job configuration) with them reporting back some additional info, such as the runtime of the converted audio etc. At present, I have a script that makes a webservice call to get the 'configuration' for a conversion task, based on source files located on the worker already (we manually copy the source files to the worker, and that triggers a conversion routine). I want to change this, so that we can distribute conversion tasks ("Oy you, process this: xxx") based on availability, and in an ideal world, based on pending tasks too. There is a chance that Workers can go offline mid-conversion (but this is not likely). All the workers are Windows based, the co-ordinator can be WIndows or Linux. I have (in my initial searches) come across the following - and I know that some are cross-dependent: Celery (with RabbitMQ) Twisted Django Using a framework, rather than home-brewing, seems to make more sense to me right now. I have a limited timeframe in which to develop this functional extension. An additional consideration would be using a Framework that is compatible with PyQT/PySide so that I can write a simple UI to display Queue status etc. I appreciate that the specifics above are a little vague, and I hope that someone can offer me a pointer or two. Again: I am looking for general advice on which Python framework to investigate further, for developing a Server/Worker 'Queue management' solution, for non-web activities (this is why DJango didn't seem the right fit).

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• C++ Suppress Automatic Initialization and Destruction

  - by Travis G

  How does one suppress the automatic initialization and destruction of a type? While it is wonderful that T buffer[100] automatically initializes all the elements of buffer, and destroys them when they fall out of scope, this is not the behavior I want. #include <iostream> static int created = 0, destroyed = 0; struct S { S() { ++created; } ~S() { ++destroyed; } }; template <typename T, size_t KCount> class Array { private: T m_buffer[KCount]; public: Array() { // some way to suppress the automatic initialization of m_buffer } ~Array() { // some way to suppress the automatic destruction of m_buffer } }; int main() { { Array<S, 100> arr; } std::cout << "Created:\t" << created << std::endl; std::cout << "Destroyed:\t" << destroyed << std::endl; return 0; } The output of this program is: Created: 100 Destroyed: 100 I would like it to be: Created: 0 Destroyed: 0 My only idea is to make m_buffer some trivially constructed and destructed type like char and then rely on operator[] to wrap the pointer math for me, although this seems like a horribly hacked solution. Another solution would be to use malloc and free, but that gives a level of indirection that I do not want.

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• Accessing program information that gdb sees in C++

  - by anon

  I have a program written in C++, on Linux, compiled with -g. When I run it under gdb, I can 1) set breakpoints 2) at those breakpoints, print out variables 3) see the stackframe 4) given a variable that's a structure, print out parts of the structure (i.e. how ddd displays information). Now, given that my program is compiled with "-g" -- is there anyway that I can access this power within my program itself? I.e. given that my program is compiled with "-g", is there some std::vector<string> getStackFrame(); function I can call to get the current stackframe at the current point of execution? Given a pointer to an object and it's type ... can I do std::vector getClassMember(class_name); ? I realize the default answer is "no, C++ doesn't support that level of introspection" -- however, recall I'm on linux, my program is compiled with "-g", and gdb can do it, so clearly the inforamtion is there. Question is: is there some API for accessing it? EDIT: PS Naysers, I'd love to see a reason for closing this question.

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• How to optimize paging for large in memory database

  - by snakefoot

  I have an application where the entire database is implemented in memory using a stl-map for each table in the database. Each item in the stl-map is a complex object with references to other items in the other stl-maps. The application works with a large amount of data, so it uses more than 500 MByte RAM. Clients are able to contact the application and get a filtered version of the entire database. This is done by running through the entire database, and finding items relevant for the client. When the application have been running for an hour or so, then Windows 2003 SP2 starts to page out parts of the RAM for the application (Eventhough there is 16 GByte RAM on the machine). After the application have been partly paged out then a client logon takes a long time (10 mins) because it now generates a page fault for each pointer lookup in the stl-map. I can see it is possible to tell Windows to lock memory in RAM, but this is generally only recommended for device drivers, and only for "small" amounts of memory. I guess a poor mans solution could be to loop through the entire memory database, and thus tell Windows we are still interested in keeping the datamodel in RAM. I guess another poor mans solution could be to disable the pagefile completely on Windows. I guess the expensive solution would be a SQL database, and then rewrite the entire application to use a database layer. Then hopefully the database system will have implemented means to for fast access. Are there other more elegant solutions ?

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• Adding and sorting a linked list in C

  - by user1202963

  In my assignment, I have to write a function that takes as arguments a pointer to a "LNode" structure and an integer argument. Then, I have to not only add that integer into the linked list, but also put place it so that the list is in proper ascending order. I've tried several various attempts at this, and this is my code as of posting. LNode* AddItem(LNode *headPtr, int newItem) { auto LNode *ptr = headPtr; ptr = malloc(sizeof(LNode)); if (headPtr == NULL) { ptr->value = newItem; ptr->next = headPtr; return ptr; } else { while (headPtr->value > newItem || ptr->next != NULL) { printf("While\n"); // This is simply to let me know how many times the loop runs headPtr = headPtr->next; } ptr->value = newItem; ptr->next = headPtr; return ptr; } } // end of "AddItem" When I run it, and try to insert say a 5 and then a 3, the 5 gets inserted, but then the while loop runs once and I get a segmentation fault. Also I cannot change the arguments as it's part of a skeletal code for this project. Thanks to anyone who can help. If it helps this is what the structure looks like typedef struct LNode { int value; struct LNode *next; } LNode;

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• C++ -- Why should we use operator -> to access member functions of a SmartPtr?

  - by q0987

  Hello all, The question is given in the last two lines of code. template<class T> // template class for smart class SmartPtr { // pointers-to-T objects public: SmartPtr(T* realPtr = 0); T* operator->() const; T& operator*() const; T* Detach( void ) { T* pData = pointee; pointee = NULL; return pData; } private: T *pointee; ... }; class TestClass {} SmartPtr<TestClass> sPtr(new TestClass); TestClass* ptrA = sPtr->Detach(); // why I always see people use this method to access member functions of a Smart pointer. We can use sPtr-> b/c we have defined operator->() in SmartPtr. TestClass* ptrB = sPtr.Detach(); // Question: Is this a valid C++ way? If not, why? Thank you

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• My java program seems to be skipping over the try{}, executing the catch{} and then throwing a NullPointerException. What should I do?

  - by Matt Bolopue

  I am writing a program that calculates the number of words, syllables, and sentences in any given text file. I don't need help finding those numbers, however my program (which currently should only find the number of words in the text file) will not import the text file even when I type in the name of the file correctly. The text file is in the same folder as the source code. Instead it tells me every time that what I typed in has the wrong file extension (see my catch{}) and then proceeds to throw a null pointer. I am at a loss for what could be causing it. Any suggestions? import java.io.*; import java.util.*; public class Reading_Lvl_Calc { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int words = 0; String fileName; Scanner scan; Scanner keyread = new Scanner(System.in); System.out.println("Please enter a file name (or QUIT to exit)"); fileName = keyread.nextLine(); File doc = new File(fileName); //while(scan.equals(null)){ try { scan = new Scanner(doc); } catch(Exception e) { if(fileName.substring(fileName.indexOf(".")) != ".txt") System.out.println("I'm sorry, the file \"" + fileName + "\" has an invalid file extension."); else System.out.println("I am sorry, the file \"" + fileName + " \" cannot be found.\n The file must be in the same directory as this program"); scan = null; } // } while(scan.hasNext()){ words++; scan.next(); } System.out.println(words); } }

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• Issue selenium code maintenance

  - by Rajasankar

  I want to group the common methods in one file and use it. For example, login to a page using selenium may be used in multiple times. Define that in class A and call it in class B. However, it throws null pointer exception. class A has public void test_Login() throws Exception { try{ selenium.setTimeout("60000"); selenium.open("http://localhost"); selenium.windowFocus(); selenium.windowMaximize(); selenium.windowFocus(); selenium.type("userName", "admin"); selenium.type("password", "admin"); Result=selenium.isElementPresent("//input[@type='image']"); selenium.click("//input[@type='image']"); selenium.waitForPageToLoad(Timeout); } catch(Exception ex) { System.out.println(ex); ex.printStackTrace(); } } with all other java syntax in class B public void test_kk() throws Exception { try { a.test_Login(); } catch(Exception ex) { System.out.println(ex); ex.printStackTrace(); } } with all syntax. When I execute class B, I got this error, java.lang.NullPointerException at A.test_Login(A.java:32) at B.test_kk(savefile.java:58) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at com.thoughtworks.selenium.SeleneseTestCase.runBare(SeleneseTestCase.j ava:212) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at junit.textui.TestRunner.doRun(TestRunner.java:116) at junit.textui.TestRunner.doRun(TestRunner.java:109) at junit.textui.TestRunner.run(TestRunner.java:77) at B.main(B.java:77) I hope someone must have tried this before. I may miss something here.

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• SWIG_NewPointerObj and values always being nil

  - by Tom J Nowell

  I'm using SWIG to wrap C++ objects for use in lua, and Im trying to pass data to a method in my lua script, but it always comes out as 'nil' void CTestAI::UnitCreated(IUnit* unit){ lua_getglobal(L, "ai"); lua_getfield(L, -1, "UnitCreated"); swig_module_info *module = SWIG_GetModule( L ); swig_type_info *type = SWIG_TypeQueryModule( module, module, "IUnit *" ); SWIG_NewPointerObj(L,unit,type,0); lua_epcall(L, 1, 0); } Here is the lua code: function AI:UnitCreated(unit) if(unit == nil) then game:SendToConsole("I CAN HAS nil ?") else game:SendToConsole("I CAN HAS UNITS!!!?") end end unit is always nil. I have checked and in the C++ code, the unit pointer is never invalid/null I've also tried: void CTestAI::UnitCreated(IUnit* unit){ lua_getglobal(L, "ai"); lua_getfield(L, -1, "UnitCreated"); SWIG_NewPointerObj(L,unit,SWIGTYPE_p_IUnit,0); lua_epcall(L, 1, 0); } with identical results. Why is this failing? How do I fix it?

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• Deleting from 2 arrays of dictionaries

  - by Matt Winters

  I have an array of dictionaries loaded from a plist (below) called arrayHistory. <plist version="1.0"> <array> <dict> <key>item</key> <string>1</string> <key>result</key> <string>8.1</string> <key>date</key> <date>2009-12-15T19:36:59Z</date> </dict> ... </array> </plist> I filter this array based on 'item' so that a second array, arrayHistoryDetail has the same structure as arrayHistory but only contains e.g. 'item's equal to '1'. These detail items are successfully displayed in a tableView. I then want to select an item from the tableView, and delete it from the tableView data source, arrayHistoryDetail (line 2 in the code below) - works, then I want to delete the item from the tableView itself (line 3 in the code below) - also works. My problem is that I also need to delete it from the original arrayHistory, so I tried the following: created a temporary dictionary as an ivar: NSMutableDictionary *tempDict; @property (nonatomic, retain) NSMutableDictionary *tempDict; Then my thinking was to make a copy in line 1 and remove it from the original array in line 4. 1 tempDict = [arrayHistoryDetail objectAtIndex: indexPath.row]; 2 [arrayHistoryDetail removeObjectAtIndex: indexPath.row]; 3 [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; 4 [arrayHistory removeObject:tempDict]; Didn't work. Could someone please guide me in the right direction. I'm thinking that tempDict is a pointer and that removeObject needs a copy? I don't know. Thanks.

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• Automatically converting an A* into a B*

  - by Xavier Nodet

  Hi, Suppose I'm given a class A. I would like to wrap pointers to it into a small class B, some kind of smart pointer, with the constraint that a B* is automatically converted to an A* so that I don't need to rewrite the code that already uses A*. I would therefore want to modify B so that the following compiles... struct A { void foo() {} }; template <class K> struct B { B(K* k) : _k(k) {} //operator K*() {return _k;} //K* operator->() {return _k;} private: K* _k; }; void doSomething(A*) {} void test() { A a; A* pointer_to_a (&a); B<A> b (pointer_to_a); //b->foo(); // I don't need those two... //doSomething(b); B<A>* pointer_to_b (&b); pointer_to_b->foo(); // 'foo' : is not a member of 'B<K>' doSomething(pointer_to_b); // 'doSomething' : cannot convert parameter 1 from 'B<K> *' to 'A *' } Note that B inheriting from A is not an option (instances of A are created in factories out of my control)... Is it possible? Thanks.

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• Lite-Javascript Gallery - Can I position the img absolutely in relationship to the lis?

  - by blackessej

  I have a lite-javascript run image gallery. The javascript grabs each element in the list and places it as a background in the parent element. Then the CSS styles the thumbnails as small blocks with a defined height/width. A click-event for each object toggles it’s child’s element’s visibility and adds an “active” class name to the . Using CSS, I'm trying to place the absolutely to make it appear at the same position for each thumb, but it's moving in relation to the thumbs. Here's the CSS: #jgal li { background-position:50% 50%; background-repeat:no-repeat; border:solid #999 4px; cursor:pointer; display:block; float:left; height:60px; width:60px; margin-bottom:14px; margin-right:14px; opacity:0.5; } #jgal li img { position:absolute; top:0px; left:210px; display:none; } And the site: http://www.erisdesigns.net Thanks in advance for any help!

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• A public struct inside a class

  - by Koning Baard

  I am new to C++, and let's say I have two classes: Creature and Human: /* creature.h */ class Creature { private: public: struct emotion { /* All emotions are percentages */ char joy; char trust; char fear; char surprise; char sadness; char disgust; char anger; char anticipation; char love; }; }; /* human.h */ class Human : Creature { }; And I have this in my main function in main.cpp: Human foo; My question is: how can I set foo's emotions? I tried this: foo->emotion.fear = 5; But GCC gives me this compile error: error: base operand of '-' has non-pointer type 'Human' This: foo.emotion.fear = 5; Gives: error: 'struct Creature::emotion' is inaccessible error: within this context error: invalid use of 'struct Creature::emotion' Can anyone help me? Thanks P.S. No I did not forget the #includes

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• jQuery: If user clicks out of div

  - by Paul Knopf

  I am creating a popup in query. All is well with the popup on hover. I made it see a timer starts when user's mouse leaves the div to close it. If he enters the div again before the timer is done, then the timer is cleared. This is fine, but what if a user clicks out of the div? I want that to also close the div. The only problem is that I don't want to attach click events to the wrapper on the page (because it includes the popout menu). I have seen techniques that wraps entire screen with a transparent div, and then attach a click event to hit. Although this may work, it confuses the user if he clicks the hidden div intending to click a link. He will have to click the link twice. Once two close the div (hiding the link), and another time to actually click think. Also, you loose in mouse cursors attached to any masked elements on the page (such as links cursor pointer, etc). There has to be a way to check if the user clicked out of the div without a modal and without attaching events to the entire page (page wrappers and child elements included). onclicksomewhereelse="closeme();" lol.

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• Better language or checking tool?

  - by rwallace

  This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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• Array's index and argc signedness

  - by tusbar

  Hello, The C standard (5.1.2.2.1 Program startup) says: The function called at program startup is named main. [...] It shall be de?ned with a return type of int and with no parameters: int main(void) { /* ... */ } or with two parameters [...] : int main(int argc, char *argv[]) { /* ... */ } And later says: The value of argc shall be nonnegative. Why shouldn't argc be defined as an unsigned int, argc supposedly meaning 'argument count'? Should argc be used as an index for argv? So I started wondering if the C standard says something about the type of array's index. Is it signed? 6.5.2.1 Array subscripting: One of the expressions shall have type ‘‘pointer to object type’’, the other expression shall have integer type, and the result has type ‘‘type’’. It doesn't say anything about its signedness (or I didn't find it). It is pretty common to see codes using negatives array indexes (array[-1]) but isn't it undefined behavior? Should array's indexes be unsigned?

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• local vs core contoller

  - by latvian

  Hi, I am adding new column and action in the local admin app/code/local/Mage/Adminhtml/Block/Catalog/Product/Grid.php which works fine, however. The local controller/app/code/local/Mage/Adminhtml/Block/Catalog/Product.php is not being used or is not overloading the admin one /app/code/core/Mage/Adminhtml/Block/Catalog/Product.php. This is almost fresh install of Magento 1.4.0.1. I am the only one working, so i know it is not overloaded by some custom controller. I have disabled all custom modules. I have rolled back most of my changes. I have checked /etc/Modules/Mage_Catalog.xml. Refreshed cache all possible ways, loged in and out. Nothing....still using the core contoller copy. why? How do you troubleshoot, meaning, at what moment magento decides using between core or local copies? ...its even more strange because it does not parse local Adminhtml config.xml but uses local Adminthml copy of Blocks. Any pointer would help. I would like to keep everything in local code. Thank You, Margots

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• How to access the element of a list/vector that passed by reference in C++

  - by bsoundra

  Hi all, The problem is passing lists/vectors by reference int main(){ list<int> arr; //Adding few ints here to arr func1(&arr); return 0; } void func1(list<int> * arr){ // How Can I print the values here ? //I tried all the below , but it is erroring out. cout<<arr[0]; // error cout<<*arr[0];// error cout<<(*arr)[0];//error //How do I modify the value at the index 0 ? func2(arr);// Since it is already a pointer, I am passing just the address } void func2(list<int> *arr){ //How do I print and modify the values here ? I believe it should be the same as above but // just in case. } Is the vectors any different from the lists ? Thanks in advance. Any links where these things are explained elaborately will be of great help. Thanks again.

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• pthread_create followed by pthread_detach still results in possibly lost error in Valgrind.

  - by alesplin

  I'm having a problem with Valgrind telling me I have some memory possible lost: ==23205== 544 bytes in 2 blocks are possibly lost in loss record 156 of 265 ==23205== at 0x6022879: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==23205== by 0x540E209: allocate_dtv (in /lib/ld-2.12.1.so) ==23205== by 0x540E91D: _dl_allocate_tls (in /lib/ld-2.12.1.so) ==23205== by 0x623068D: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread-2.12.1.so) ==23205== by 0x758D66: MTPCreateThreadPool (MTP.c:290) ==23205== by 0x405787: main (MServer.c:317) The code that creates these threads (MTPCreateThreadPool) basically gets an index into a block of waiting pthread_t slots, and creates a thread with that. TI becomes a pointer to a struct that has a thread index and a pthread_t. (simplified/sanitized): for (tindex = 0; tindex < NumThreads; tindex++) { int rc; TI = &TP->ThreadInfo[tindex]; TI->ThreadID = tindex; rc = pthread_create(&TI->ThreadHandle,NULL,MTPHandleRequestsLoop,TI); /* check for non-success that I've omitted */ pthread_detach(&TI->ThreadHandle); } Then we have a function MTPDestroyThreadPool that loops through all the threads we created and cancels them (since the MTPHandleRequestsLoop doesn't exit). for (tindex = 0; tindex < NumThreads; tindex++) { pthread_cancel(TP->ThreadInfo[tindex].ThreadHandle); } I've read elsewhere (including other questions here on SO) that detaching a thread explicitly would prevent this possibly lost error, but it clearly isn't. Any thoughts?

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• How to convert a lambda to an std::function using templates

  - by retep998

  Basically, what I want to be able to do is take a lambda with any number of any type of parameters and convert it to an std::function. I've tried the following and neither method works. std::function([](){});//Complains that std::function is missing template parameters template <typename T> void foo(function<T> f){} foo([](){});//Complains that it cannot find a matching candidate The following code does work however, but it is not what I want because it requires explicitly stating the template parameters which does not work for generic code. std::function<void()>([](){}); I've been mucking around with functions and templates all evening and I just can't figure this out, so any help would be much appreciated. As mentioned in a comment, the reason I'm trying to do this is because I'm trying to implement currying in C++ using variadic templates. Unfortunately, this fails horribly when using lambdas. For example, I can pass a standard function using a function pointer. template <typename R, typename...A> void foo(R (*f)(A...)) {} void bar() {} int main() { foo(bar); } However, I can't figure out how to pass a lambda to such a variadic function. Why I'm interested in converting a generic lambda into an std::function is because I can do the following, but it ends up requiring that I explicitly state the template parameters to std::function which is what I am trying to avoid. template <typename R, typename...A> void foo(std::function<R(A...)>) {} int main() { foo(std::function<void()>([](){})); }

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