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  • c++ compilation error

    - by clamp
    hello, i got a compile error which i do not understand. i have a h/cpp file combination that does not contain a class but just defines some utility functions. when i try to use a struct that is defined in another class i get the error: error C2027: use of undefined type so, stripped down to the problem, the h file looks like this namespace A { void foo(B::C::SStruct const & Var); } the definition of SStruct is in a class which is in another h-file, that is of course included. namespace B { Class C { struct SStruct { }; } } what am i missing here? thanks!

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  • Why does coffeescript generate classes like this?

    - by ryeguy
    Given the following coffeescript code: class Animal constructor: (@name) -> speak: (things) -> "My name is #{@name} and I like #{things}" This is generated: var Animal = (function() { function Animal(name) { this.name = name; } Animal.prototype.speak = function(things) { return "My name is " + this.name + " and I like " + things; }; return Animal; })(); But why isn't this more idiomatic code generated? var Animal = function Animal(name) { this.name = name; }; Animal.prototype.speak = function(things) { return "My name is " + this.name + " and I like " + things; }; I know that coffeescript wraps a lot of stuff in anonymous functions to control scope leak, but what could leak here?

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  • Callback Timer function in C++

    - by user3596609
    I am trying to implement a callback timer function in C++ which should do a callback after a timeout. I am listening on a socket and then waiting for messages on it. so if I have something like getMessages() and I want to pass the timer function in it as an argument. So how can it be implemented that after the receive of a message, the timer is started and the callback happens if there is a timeout before the next messages arrives. I am new to callback functions. Any help is greatly appreciated. Thanks!

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  • Issue with this function. The code is not executing.

    - by Tapha
    The function is supposed to update the values in the database. Here is the code: //Functions //Function to Update users networth function update_net($name) { //Get worth & balance at the time $sql_to_get_worth_balance = "SELECT * FROM user WHERE username = '$name'"; $sql_query = mysql_query($sql_to_get_worth_balance); while ($rows = mysql_fetch_assoc($sql_query)) { $worth = $rows['worth']; $balance_ = $rows['cash_balance']; } //Get net_worth now $new_net_worth = $worth + $balance; //Update net_worth $sql_for_new_worth = "UPDATE user SET net_worth = '$new_net_worth'"; $sql_worth_query = mysql_query($sql_worth); } It is used here: //Get username $username = $_SESSION['username']; if (isset($username)) { //Update networth $update_worth = update_net($username);

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  • What is the smallest Windows header I can #include to define DWORD?

    - by j_random_hacker
    I have a small header file of my own which declares a couple of functions, one of which has a return type of DWORD. I'm reluctant to drag in windows.h just to get the official definition of this type since that file is huge, and my header will be used in a number of source modules that don't otherwise need it. Of course, in practice I know that DWORD is just unsigned int, but I'd prefer the more hygienic approach of including an official header file if possible. On this page it says that DWORD is defined in windef.h, but unfortunately including just this small file directly leads to compilation errors -- apparently it expects to be included by other headers. (Also, the fact that my file is a header file also means I can't just declare WIN32_LEAN_AND_MEAN, since the source file that #includes my file might need this to be left undefined.) Any ideas? I know it's not the end of the world -- I can just continue to #include <windows.h> -- but thought someone might have a better idea!

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  • Is pthread_spin_trylock safe inside of sigsegv handler of multithreaded application?

    - by TWMouton
    I am trying to implement a handler that on SIGSEGV will collect some information such as process-id, thread-id and a backtrace and write this information to a file/pipe/socket. The problem lies in that there is the (probably pretty high) possibility that if one thread experienced a SIGSEGV that the others will shortly follow. If two threads happen to make it to the bit of code where they're writing their report out at the same time then they'll interleave their writing (to the same file). I know that I should only be using async-signal-safe functions as detailed in signal(7) I also have seen at least two cases here and video linked in top answer here where others have used pthread_spin_trylock to get around this problem. Is this a safe way to prevent the above problem?

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  • overloading new operator in c++

    - by Angus
    I have a code for best fit algorithm. I want to try to use the best fit algorithm using the operator new. Every time I create an object I should give it from the already allocated memory say, 1]20 2]12 3]15 4]6 5]23 respectively. which ever minimum amount fits to the objects size(eg.21) I wanted to do it for different object types, so I need to write the overloaded operator new to be common functionality for all the class objects. Can I do it through friend functions, or is there any possible way to do it.

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  • PotgreSQL 2D array to rows

    - by PostGreSQL newbie
    Hello, I am new to PostgreSQL array's. I am trying to a write a procedure to convert array-into-rows, and wanted following output: alphabet | number ---------+---------- A | 10 B | 10 C | 6 D | 9 E | 3 from following: id | alphabet_series -------+-------------------------------------------------------------------------------------------------- 1 | {{A,10},{B,10},{C,6},{D,9},{E,3},{F,9},{I,10},{J,17},{K,16},{L,17},{M,20},{N,13},{O,19}} I have searched for array-to-rows functions, but they all seems to accept 1-d array. but in this case, it is 2-d array. Any pointers will be appreciated. Many thanks.

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  • Method to register method to be called when event is raised

    - by zaidwaqi
    I have a Panel which contains 20 PictureBox controls. If a user clicks on any of the controls, I want a method within the Panel to be called. How do I do this? public class MyPanel : Panel { public MyPanel() { for(int i = 0; i < 20; i++) { Controls.Add(new PictureBox()); } } // DOESN'T WORK. // function to register functions to be called if the pictureboxes are clicked. public void RegisterFunction( <function pointer> func ) { foreach ( Control c in Controls ) { c.Click += new EventHandler( func ); } } } How do I implement RegisterFunction()? Also, if there are cool C# features that can make the code more elegant, please share.

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  • Why does OpenGL have to completely break backwards compatablity?

    - by directx
    I'm not sure if this only applies to JOGL or the entire OpenGL project in general. But there seems to be a vast difference between versions 3.x and 2.x; Code that works on one version will not work on another. It looks to me like the library designers intentionally renamed various classes, packages, and functions just to screw up the existing code. I've never seen anything like this before. The problem is I'm not sure which library to use now, and when looking at code it's not so easy to figure out whether it's supposed to run on 2.x or 3.x.

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  • How to call AJAX API function from Windows App?

    - by stiopa
    Some company is providing me with web-based API for using their services. I have no problem calling this API functions from within web brower: <html xmlns="http://www.w3.org/1999/xhtml"> <head> <script type="text/javascript" src="http://someaddress.com?&key=somekey"></script> <script type="text/javascript"> var object = new SomeObject(); object.SomeFunction(); </script> </head> I am interested in return value of SomeFunction(). How would I get this return value from windows application?

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  • Doubt about a particular pattern of Javascript class definition

    - by fenderplayer
    Recently i saw the following code that creates a class in javascript: var Model.Foo = function(){ // private stuff var a, b; // public properties this.attr1 = ''; this.attr2 = ''; if(Model.Foo._init === 'undefined'){ Model.Foo.prototype = { func1 : function(){ //...}, func2 : function(){ //... }, //other prototype functions } } Model.Foo._init = true; } // Instantiate and use the class as follows: var foo = new Model.Foo(); foo.func1(); I guess the _init variable is used to make sure we don't define the prototypes again. Also, i feel the code is more readable since i am placing everything in a function block (so in oop-speak, all attributes and methods are in one place). Do you see any issues with the code above? Any pitfalls of using this pattern if i need to create lots of classes in a big project?

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  • returning values from function or method multiple times by only calling the class once

    - by Sokhrat Sikar
    I have a members.php file that shows my websites members. I echo members name by using foreach method. A method of Members class returns an array, then I use foreach loop in the members.php file to echo the members. I am trying to aovid writing php code in my members.php file. Is there a way to avoid using foreach inside members.php file? For example, is it possible to return value from a method couple of times? (by only calling the object once). Just like how we normally call the functions? This question doesn't make sense, but I am just trying to see if there is a away around this issue?

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  • How can I login linux using C or C++

    - by jnblue
    I need to programmely switch the current user to another,then the followed code should be executed in the environment(such as path,authority..) of another user. I've find the 'chroot()','setuid()' may be associated with my case, but these functions need the root authority, I don't have root authority, but I have the password of the second user. what should I do? I have tried shell "su - " can switch current user, can this command help me in my C++ code? Don't laugh at me if my question is very stupid, I'm a true freshman on linux. :) Thanks!

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  • wordpress: previous_post_link() / next_post_link() placeholder

    - by superUntitled
    I am having trouble with the previous_post_link() and next_post_link() functionality. When there is no previous post, the function previous_post_link() does not display a link, likewise for the next_post_link() and the last post. I would like to have a placeholder image so that the design stays consistent. Currently I have images of green arrows pointing left and right, I would like to place an image of a grey arrow if there are no more posts to go back to. Is there a way to use the next_post_link()/previous_post_link() functions but not have the link removed. I also wonder if there is a way for the links to cycle, so that if you come to the most recent post, the next post link would bring you back to the first post.

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  • Getting imagename and make link from <img> with jQuery

    - by Bulan
    With jQuery, I want to make all images under a specific path on a site clickable and showing a big image using Fancybox, which is a lighbox variant plugin for jQuery. My small images are located under "images/products/small", the big ones under "images/products/big" and the imagename is always the same The page is showing the image with the following code: <img src="images/products/small/hat.jpg" alt="Nice hat"> What i want is some jQuery script that makes this into: <a href="images/products/big/hat.jpg" class="fancybox"><img src="images/products/small/hat.jpg" alt="Nice hat"></a> Maybe the part with setting class on the link tag can be skipped and just activate fancybox on the element directly with $(elm).fancybox(); I was looking around a bit and it looks like the jQuery functions "attr" and "wrap" might be useful, but with my currently limited jQuery skills I can't really connect the dots.

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  • MySQL LEFT JOIN issue with three WHERE statements

    - by jhat
    I am building a note taking app for myself with tag filtering functions, but am having an issue when trying to grab notes with the tags. The tag filter needs to use AND not IN, because it will help better narrow down what I am looking for. My tables are configured like this: + notes note_id | note_title | note_uid + tags tag_id | tag_title + notes_tags nt_id | nt_note_id | nt_tag_id The notes_tags table keeps track of all notes' tags. I am not worried about returning any information about tags, so here is an example LEFT JOIN I am using currently to only get notes with only 1 tag. SELECT * FROM notes_tags LEFT JOIN notes ON note_id = nt_note_id WHERE note_uid IN ( 1 ) AND nt_tag_id = 10 This query runs perfect, it grabs all of the notes with that single tag. However, I am having issues "pinpointing" my notes using a query like this: SELECT * FROM notes_tags LEFT JOIN notes ON note_id = nt_note_id WHERE note_uid IN ( 1 ) AND nt_tag_id = 10 AND nt_tag_id = 11 What am I doing wrong with the syntax?

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  • More compact way to do this?

    - by Macha
    I have a couple of functions that loop around the surrounding cells of a cell. The grid is contained inside an array. In my code, I have checks to make sure it's not one of the edge cells, as checking an undefined cell causes an error. As such, I have code like this: if(x > 0) { var firstX = x - 1; } else { var firstX = x; } if(x < 199) { var lastX = x + 1; } else { var lastX = x; } if(y > 0) { var firstY = y - 1; } else { var firstY = y; } if(y < 199) { var lastY = y + 1; } else { var lastY = y; } A lot of lines of code to do very little. Is there a more elegant way to do this?

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  • Page layout breaks only in Opera which is weird?

    - by Qwibble
    Okay so I'm working on an admin panel, in which everything should always be only within the view port until you hit the minimum widths and heights set. The current version of it can be seen here (its still in development) : http://qwibbledesigns.co.uk/preview/Admin/ In layout terms, it works flawlessly in all browsers, even down to ie6 =D. However, opera doesn't like it, and for some reason, always add's extra space to the bottom of the page, making it have an extra scrollbar, and I can't fathom it out which is highly annoying. Jquery is used to set the height of the container, sidebar, and content area so that they're always within the browser view port, and these functions rerun when the window is resized. I therefore cannot work out the the life of me what's wrong with opera. Would anyone mind taking a look and seeing if they can work it out? =D

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  • What is the precedence of characters when sorting in MySQL, PHP, or just in general?

    - by FireCoding
    Question: Where can I find the precedence of characters when sorting in MySQL, PHP, or just in general on Linux and Windows OS? For example, everybody knows that a comes before b when performing an ascending sort on a string in MySQL. But what about other characters? Does the dollar-sign $ come before asterisk * ? Does a space come before an exclamation-mark? etc... What dictates the sort order? Does it use underlying ascii / UTF-8 values? Is it different for different technologies? Technologies to consider: Databases - MySQL / SQL / SQLite / Oracle / etc Programming languages (for string-sorting functions) - PHP / Javascript / ASP.NET / Visual C# / Python / Ruby / Objective C OS (i.e., sorting files by filename) - Windows / Linux / MacOS / iOS / Android

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  • Parsing C# Script into Java

    - by pantaryl
    I'm looking for a way to easily read in a C# file and place it into a Java Object for database storage (storing the class name, functions, variables, etc). I'm making a Hierarchical State Machine AI Building Tool for a game I'm creating and need to be able to import an existing C# file and store it in a database for retrieval in the future. Does anyone know of any preexisting libraries for parsing C# files? Something similar to JavaParser? Thanks everyone! EDIT: This needs to be part of my Java Project. I'll be loading in the C# files through my Java Application and saving it into my db4o database.

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  • Multithreaded SDL error in C++

    - by wyatt
    I'm building a program in C++, using SDL, and am occasionally receiving this error: * glibc detected * ./assistant: double free or corruption (!prev) It's difficult to replicate, so I can't find exactly what's causing it, but I just added a second thread to the program, and neither thread run on its own seems to cause the error. The threads don't share any variables, though they both run the functions SDL_BlitSurface and SDL_Flip. Could running these concurrently throw up such an error, or am I barking up the wrong tree? If this is the cause, should I simply throw a mutex around all SDL calls? Thanks

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  • Any good idioms for error handling in straight C programs?

    - by Will Hartung
    Getting back in to some C work. Many of my functions look like this: int err = do_something(arg1, arg2, arg3, &result); With the intent the result gets populated by the function, and the return value is the status of the call. The darkside is you get something naive like this: int err = func1(...); if (!err) { err = func2(...); if (!err) { err = func3(...); } } return err; I could macro it I suppose: #define ERR(x) if (!err) { err = (x) } int err = 0; ERR(func1(...)); ERR(func2(...)); ERR(func3(...)); return err; But that only works if I'm chaining function calls, vs doing other work. Obviously Java, C#, C++ have exceptions that work very well for these kinds of things. I'm just curious what other folks do and how other folks do error handling in their C programs nowadays.

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  • Undefined reference to "func" when compiled with GCC

    - by hotlemontea
    I implement a link list in two files in linklist.h and linklist.c, and I call some functions defined in linklist.h in main function of main.c. linklist.h is included in both linklist.c and main.c. When I compile this program by GCC with Makefile, the error named "undefined reference to xxx" occurs. I think my Makefile is written correctly as below. So what is the possible reason for this linking error CC=gcc CFLAGS= -g -O2 TARGET=target OBJECTS=main.o linklist.o TARGET: $(OBJECTS) $(CC) $(CFLAGS) $(OBJECTS) -o $(TARGET) clean: rm target $(OBJECTS) main.o:linklist.h linklist.o:linklist.h

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  • Why does the Win32-API have so many custom types?

    - by sub
    I'm new to the Win32 API and the many new types begin to confuse me. Some functions take 1-2 ints and 3 UINTS as arguments. Why can't they just use ints? What are UINTS? Then, there are those other types: DWORD LPCWSTR LPBOOL Again, I think the "primitive" C types would be enough - why introduce 100 new types? This one was a pain: WCHAR* I had to iterate through it and push_back every character to an std::string as there wasn't another way to convert it to one. Horrible. Why WCHAR? Why reinvent the wheel? They could have just used char* instead, or?

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