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  • Why does the assignment operator return a value and not a reference?

    - by Nick Lowman
    I saw the example below explained on this site and thought both answers would be 20 and not the 10 that is returned. He wrote that both the comma and assignment returns a value, not a reference. I don't quite understand what that means. I understand it in relation to passing variables into functions or methods i.e primitive types are passed in by value and objects by reference but I'm not sure how it applies in this case. I also understand about context and the value of 'this' (after help from stackoverflow) but I thought in both cases I would still be invoking it as a method, foo.bar() which would mean foo is the context but it seems both result in a function call bar(). Why is that and what does it all mean? var x = 10; var foo = { x: 20, bar: function () {return this.x;} }; (foo.bar = foo.bar)();//returns 10 (foo.bar, foo.bar)();//returns 10

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  • Is PThread a good choice for multi-platorm C/C++ multi-threading program?

    - by RogerV
    Been doing mostly Java and smattering of .NET for last five years and haven't written any significant C or C++ during that time. So have been away from that scene for a while. If I want to write a C or C++ program today that does some multi-threading and is source code portable across Windows, Mac OS X, and Linux/Unix - is PThread a good choice? The C or C++ code won't be doing any GUI, so won't need to worry with any of that. For the Windows platform, I don't want to bring a lot of Unix baggage, though, in terms of unix emulation runtime libraries. Would prefer a PThread API for Windows that is a thin-as-possible wrapper over existing Windows threading APIs. ADDENDUM EDIT: Am leaning toward going with boost:thread - I also want to be able to use C++ try/catch exception handling too. And even though my program will be rather minimal and not particularly OOPish, I like to encapsulate using class and namespace - as opposed to C disembodied functions.

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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's some simple F# code that generates the .tail IL instruction?

    - by kld2010
    I'd like to see the .tail IL instruction, but the simple recursive functions using tail calls that I've been writing are apparently optimized into loops. I'm actually guessing on this, as I'm not entirely sure what a loop looks like in Reflector. I definitely don't see any .tail opcodes though. I have "Generate tail calls" checked in my project's properties. I've also tried both Debug and Release builds in Reflector. The code I used is from Programming F# by Chris Smith, page 190: let factorial x = // Keep track of both x and an accumulator value (acc) let rec tailRecursiveFactorial x acc = if x <= 1 then acc else tailRecursiveFactorial (x - 1) (acc * x) tailRecursiveFactorial x 1 Can anyone suggest some simple F# code which will indeed generate .tail?

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  • Can single-buffer blocking WSASend deliver partial data?

    - by CodeAngry
    I've pretty much always used send() with sockets and now I'm moving onto the WSA functions. With send(), I have a sendall() helper that ensured all data is delivered even if it didn't happen in one try and a partial send occurred on first call. So, instead of learning the hard way or over-complicating code when I don't have to, decided to ask you: Can a blocking WSASend() send partial data or does it send everything before it returns or fails? Or should I check the bytes sent vs. expected to send and keep at it until everything is delivered? ANSWER: Overlapped WSASend() does not send partial data but if it does, it means the connection has terminated. I've never encountered the case yet.

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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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  • Are sessions modifiable by the client/user?

    - by Sev
    In my PHP Web-App I use sessions to store the user's data. For exmaple, if a user logs in, then an instance of the User class is generated and stored in a Session. I have access levels associated with each user to determine their privileges. Store the user in a session by: $_SESSION['currentUser'] = new User($_POST['username']); For example: if($_SESSION['currentUser'] -> getAccessLevel() == 1) { //allow administration functions } where getAccessLevel() is simply a get method in the User class that returns the _accesslevel member variable. Is this secure? Or can the client somehow modify their access level through session manipulation of some sort?

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  • jQuery does not execute on dynamically loaded content,, even on a click events.

    - by sxv
    I have two document.ready functions. The first loads content into div#header. The second one performs a hide function and then a toggle function on the newly loaded content. I am not sure if this is a queueing issue or something, but not even the alert() below is executed when I click the loaded content. Thanks. <script type="text/javascript"> $(document).ready(function() { $("#header").load("/documents/collegeradioheader.txt"); }); </script> <script type="text/javascript"> $(document).ready(function() { $(".hideme").hide(); $(".slick-toggle").click(function() { alert('hi'); $(this).parent().next('div').slideToggle('fast'); .siblings('div:visible').slideUp('fast'); }); }); </script>

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  • Change IP settings using C++

    - by Chris
    How do I change the IP settings of a Windows CE 6 box Programatically via C++? Functions for Windows might also work. I found that I can change the hostname via sethostname but couldn't find how to change IP address settings such as: IP Address DHCP Subnet Gateway DNS1 / DNS2 WINS1 / WINS2 Any advice / pointers would be great. Thanks. P.s. How would you get the box to update to those settings - is a refresh or the programming equivalent of ipconfig /renew required?

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  • Initializing an array after declaration

    - by robUK
    Hello, gcc 4.4.3 c89 I have the following code as a sample of what I am trying to do. I don't know the actual size of the array, until I enter the function. However, I don't think I can set the array size after I have declared it. I need it global as some other functions will need to access the device names. Many thanks for any suggestions, /* global */ char *devices_names[]; void fill_devices(size_t num_devices) { devices_names[num_devices]; /* start filling */ }

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  • why can't you use the debug/release version of a lib interchangeably

    - by user205834
    In C++, most of the libs come in Debug/Release versions. Question 1. What are the big difference between Debug and Release versions (e.g. what advantages do you have using one versus the other). Question 2. A lib is just has an implementation of the functions, how does a function implementation change if you are using debug/release versions? Question 3. Can you ever build your app in debug mode and use a release version of a lib? Thanks.

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  • JclLastExceptStackListToStrings produces an empty string list

    - by Max
    I've installed JCL into Delphi 2010. In the following code try raise Exception.Create('Error Message'); except on E: Exception do begin ResultStatus := JclLastExceptStackListToStrings(sl, True, True, True, True); end; end; Also I have this call in the initialization section: initialization JclStartExceptionTracking; ResultStatus is false and sl is empty. I have set options to generate map and .jdbg files. Other functions, like ProcByLevel work fine. Is there something else I need to do to make JclLastExceptStackListToStrings work? From JclDebug.pas file: Last modified: $Date:: 2010-09-07 19:43:19 +0200 (mar., 07 sept. 2010) Revision: $Rev:: 3331

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  • C++: Where can I define the body for a private function?

    - by Martijn Courteaux
    Hi, I have a header like this (header guards not shown): class GameSystem { public: GameSystem(Game *pcGame); virtual ~GameSystem(); void Setup(); private: void InitGame(); void RunGame(); void ExitGame(); Game *m_pcGame; /* Properties */ int m_nWidth; int m_nHeight; int m_nFps; bool m_bFullscreen; }; Where can I define the body for InitGame(), RunGame() and ExitGame()? Can I define it in my .cpp file? If so, how? Or am I obliged to make their body in my .h file? I'm using Eclipse and I began typing: void GameSystem:: and then he doesn't suggest the private functions.

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  • how to use replace_regex_copy() from boost::algorithm library?

    - by Vincenzo
    This is my code: #include <string> #include <boost/algorithm/string/regex.hpp> string f(const string& s) { using namespace boost::algorithm; return replace_regex_copy(s, "\\w", "?"); } This is what compiler says: no matching function for call to ‘replace_regex_copy(const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::string, std::string) The link to the library: http://www.boost.org/doc/libs/1_43_0/doc/html/boost/algorithm/replace_regex_copy.html Could anyone please help? Thanks! ps. Boost library is in place, since other functions from it work fine.

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  • 7 - drupal overriding theme fucntions gettting notices

    - by welovedesign
    So I am overriding a theme function by putting the contents in my template.php module, the problem is that it it throwing up loads of undefined index notices because there are lots of functions that are defined in the module. How can I define these in the template.php file and prevent the notices. Note: I know i can turn them off 'uc_cart_block_content' => array( 'variables' => array( 'help_text' => NULL, 'items' => NULL, 'item_count' => NULL, 'item_text' => NULL, 'total' => NULL, 'summary_links' => NULL, 'collapsed' => TRUE, ), 'file' => 'uc_cart.theme.inc', ),

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  • How to import .class file in a .java file?

    - by Namratha
    Hi, What i need to do is as follows: I have a bigloo scheme program (*.scm), then using the bigloo frameworks jvm a class file is generated. I want to use this .class file from a .java file. That is, i need to import this(.class) file as i want to use some functions defined in the scheme file which is now a .class file. How do i do it in Eclipse? i have created two packages one for java and one for the .class file. Then i import the package containing the .class file. But i am not able to use the function in the .class file in the .java file. Are there any settings to be done? Please let me know how this can be done.

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  • Call function by pointer and set parametrs in memory block

    - by Ellesmess Glain
    Hi, I've little problem : I'm solving problem with calling function by pointer and passing to it parameters in continuous memory block. My goal is to have function named e.g CallFunc(void * func,void *params, unsigned int param_length); that I'll send function pointer, pointer to function's parameters and eventually parameters length and this calling function will call passed function with it's parameters. I will like write this in C/C++, but if somebody has idea, how this resolve in other language, that supports DLL generation and exportet functions, it will be fine too. Thanks for answers, Ellesmess P.S. I'm sorry about my English, but I'm Czech, thanks :o)

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  • How do I write a bash script to replace words in files and then rename files?

    - by Jason
    Hi All, I have a folder structure, as shown below: I need to create a bash script that does 4 things: It searches all the files in the generic directory and finds the string 'generic' and makes it into 'something' As above, but changes "GENERIC" to "SOMETHING" As above, but changes "Generic" to "Something" Renames any filename that has "generic" in it with "something" Right now I am doing this process manually by using the search and replace in net beans. I dont know much about bash scripting, but i'm sure this can be done. I'm thinking of something that I would run and it would take "Something" as the input. Where would I start? what functions should I use? overall guidance would be great. thanks. I am using Ubuntu 10.5 desktop edition.

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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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  • lua function as argument in C

    - by Nil
    I'm going to pass a function to another function which should operate with the passed function. For example: handler(fun1("foo",2)) handler(fun2(1e-10)) The handler is something like calling the passed function many times. I'm going to bind handler, fun1, fun2 to C-functions. fun1 and fun2 are going to return some user data with a pointer to some cpp-class so that I can further recover which function was it. The problem now is that fun1 and fun2 are going to be called before passed to handler. But I don't need this, what I need is the kind of function and its parameters. However, I should be able to call fun1 and fun2 alone without handler: fun1("bar",3) fun2(1e-5) Is it possible to get the context the function is called from? While typing the question, I realized I could do following handler(fun1, "foo",2); handler(fun2, 1e-10);

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  • Just how much do I want to make virtual?

    - by Alex
    I am writing an abstract superclass where literally every method is going to be overridden. There is some default functionality I could implement, but most of the time it's enough to leave the implementation to the subclass writer. Since just about every method is going to be overwritten, how much should I make virtual and how much should I just leave as regular methods? In the current incarnation, everything is virtual, but I still haven't let this loose to anyone to use, so the design is flexible. What advantages/disadvantages are there to virtual functions? Links to good reading material about this would be appreciated.

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  • sequencing function calls in javascript - are callbacks the only way?

    - by tim
    I read through various threads like this one for example. But it really escapes me how to accomplish the following: I have 4 functions, and want them happen one after another in sequence. Notice they are in incorrect order, to get my point across. I want the result that will output "1, 2, 3, 4' function firstFunction(){ // some very time consuming asynchronous code... console.log('1'); } function thirdFunction(){ // definitely dont wanna do this until secondFunction is finished console.log('3'); } function secondFunction(){ // waits for firstFunction to be completed console.log('2'); } function fourthFunction(){ // last function, not executed until the other 3 are done. console.log('4'); } I tried to figure out callbacks but am getting lost :( Isn't there some simple way to do this? Like looping through an array...

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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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  • 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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  • Play Framework Form "fold" method naming rationale

    - by oym
    Play Framework's (2.x) Form class has a method called fold who's usage is indicated as: anyForm.bindFromRequest().fold( f => redisplayForm(f), t => handleValidFormSubmission(t) ) Essentially, the first function parameter is what gets executed on binding failure, and the 2nd on binding success. To me it seems similar to the 'success' and 'error' callbacks of jquery's ajax function. My question is why did the Play developers call the method "fold"? As a disclaimer I am new to Scala, but I am failing to see the connection between this and the functional Scala fold operation. The only similarity is that it is a higher order function; but I don't see any combining that is taking place, nor does it delegate internally in its implementation to any of the Scala fold functions.

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