c++

Cannot run an executable binary file on another Linux System??

I'm using Ubuntu 10.04 and Qt4.6, and I've created an executable binary file on my own computer through QtCreator. Now I want to put my executable file on CentOS 5, but it seems that this executable file cannot run on CentOS. The error message is bash: ./[filename]: cannot execute binary file Now I know this comes from 32-bits and ...

Programatically detect number of physical processors/cores or if hyper-threading is active on Windows, Mac and Linux

I have a multithreaded c++ application that runs on Windows, Mac and a few Linux flavours. To make a long story short: Inorder for it to run at maximum efficiency I have to be able to instantiate a single thread per physical processor/core. Creating more threads than there are physical processors/cores degrades the performance of my prog...

How do bezier handles work?

On Wikipedia I found information about bezier curves and made a function to generate the inbetween points for a bezier polygon. I noticed that Expression Design uses bezier handles. This allows a circle to be made with 4 points each with a bezier handle. I'm just not sure mathematically how this works in relation with the formula for b...

C++ STL: How to iterate vector while requiring access to element and its index?

I frequently find myself requiring to iterate over STL vectors. While I am doing this I require access to both the vector element and its index. I used to do this as: typedef std::vector<Foo> FooVec; typedef FooVec::iterator FooVecIter; FooVec fooVec; int index = 0; for (FooVecIter i = fooVec.begin(); i != fooVec.end(); ++i, ++index) ...

Can C/C++ compiler report struct member offset

Possible Duplicate: Layout of compiled objects Hello, everyone. I'd like to ask, can compiler(e.g. Visual C++) generate a report(.txt) telling struct member offset for a struct/all structs? If so, it helps debugging quite a lot. For example, when you read disassembler code in the debugger, it can be easier to associate an off...

Creating a C++ DLL and then using it in C#

Ok I'm trying to make a C++ DLL that I can then call and reference in a c# App. I've already made a simple dll using the numberous guides out there, however when I try to reference it in the C# app I get the error Unable to load DLL 'SDES.dll': The specified module could not be found. The code for the program is as follows (bear with ...

How to track down a double free or corruption error in C++ with gdb

When I run my C++ program it crashes with this error. * glibc detected ./load: double free or corruption (!prev): 0x0000000000c6ed50 ** I'm trying to track it down using cout statement but am finding it difficult. Could gdb make this easier? How is it done? ...

pass fortran 77 function to C/C++

hello. Is it possible to pass fortran 77 function as a callback function pointer to C/C++? if so, how? information I found on the web relates to fortran 90 and above, but my legacy code base is in 77. many thanks ...

how to know whether user is completely logged in or not?

Is there a way to know whether user is completely logged in or not into system? I mean, i wanted to know whether initial login process, other initialization processes are done or not. Once those are done, i want to launch my application. So, in my service(installed before sys shutdown) i want to keep on checking whether everything is don...

C++ double division by 0.0 versus DBL_MIN

When finding the inverse square root of a double, is it better to clamp invalid non-positive inputs at 0.0 or MIN_DBL? (In my example below double b may end up being negative due to floating point rounding errors and because the laws of physics are slightly slightly fudged in the game.) Both division by 0.0 and MIN_DBL produce the same...

post and pre increment in c

Possible Duplicate: Could anyone explain these undefined behaviors (i = i++ + ++i , i = i++, etc) void main() { int a=2 , c; c=a++ + ++a + ++a + ++a; printf("%d",c); } prints 20, whereas void main() { int a=2; int c=a++ + ++a + ++a + ++a; printf("%d",c); } prints 17. Can some...

C++: Is there a way to limit access to certain methods to certain classes without exposing other private members?

I have a class with a protected method Zig::punt() and I only want it to be accessible to the class "Avocado". In C++, you'll normally do this using the "friend Avocado" specifier, but this will cause all of the other variables to become accessible to "Avocado" class; I don't want this because this breaks encapsulation. Is what I want i...

tool to find out distance in terms of no. of hops in unix

Hi! all, I am writing an application for video streaming.In the application server is required to know the distance of the client from it self in terms of hop number.My question is,is there any tool/method other than traceroute available in unix environment to find it? I also need to find out the geographical location of the client.So is...

Singleton class issue in Qt

i created a singleton class and trying to access that class in other class but getting error "cannot access private member" Setupconfig is my singleton class and i am trying to access this class in other class which have QMainWindow Error 'Setupconfig::Setupconfig' : cannot access private member declared in class 'Setupconfig' /////...

Best way to have common class shared by both C++ and Ruby?

I am currently working on a project where a team of us are designing a game, all of us are proficient in ruby and some (but not all) of us are proficient in c++. Initially we made the backend in ruby but we ported it to c++ for more speed. The c++ port of the backend has exactly the same features and algorithms as the original ruby code....

C++: static assert for const variables?

Static asserts are very convenient for checking things in compile time. A simple static assert idiom looks like this: template<bool> struct StaticAssert; template<> struct StaticAssert<true> {}; #define STATIC_ASSERT(condition) do { StaticAssert<(condition)>(); } while(0) This is good for stuff like STATIC_ASSERT(sizeof(float) == 4)...

Programming Language to manipulate an Access Database

By quote, what is the appropiate language to manipulate an Access database? A Windows user interface to manipulate an existing Access Database. ... and why? ...

How to set input focus to a shown dialog in Qt?

In a button click slot, I create and exec() a dialog with a NULL parent. Inside the dialog's constructor, I have: this->activateWindow(); this->raise(); this->setFocus(); The dialog is application modal and has strong focus. However, it does NOT respond to keyboard events until I click on it. How do I make the dialog get focus without...

Reading from istream

How can I extract data (contents) from istream without using operator>>() ?. ...

intrusive_ptr: Why isn't a common base class provided?

intrusive_ptr requires intrusive_ptr_add_ref and intrusive_ptr_release to be defined. Why isn't a base class provided which will do this? There is an example here: http://lists.boost.org/Archives/boost/2004/06/66957.php, but the poster says "I don't necessarily think this is a good idea". Why not? Update: I don't think the fact that thi...