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Mingw g++ 4.6.2 crash

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Started by belfegor March 23, 2012 03:06 PM

3 comments, last by alvaro 12 years, 1 month ago

belfegor

2,836

Author

March 23, 2012 03:06 PM

Some time ago i have downloaded CodeBlocks with Ming32 package, since it has outdated g++ version i have downloaded it separately (4.6.2) and changed compiler/linker paths acordingly, and also added new PATH path into environment variables to Mingw/bin.
Then recently tried some example code from cppreference:



#include <random>

#include <iostream>



int main()

{

    std::random_device rd;

    std::mt19937 gen(rd());

    std::uniform_int_distribution<> dis(1, 6);

    for(int n=0; n<10; ++n)

	    std::cout << dis(gen) << ' ';

    std::cout << '\n';

    return 0;

}

and it crashed:

terminate called after throwing an instance of 'std::runtime_error'
what(): random_device::random_device(const std::string&)

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

[/quote]

Got same message if i compile it from command line its same as from IDE.

Tried it on VS 2010 it works, tried it on Ubuntu 11.10 g++ 4.6.2 thru Virtual machine also works.

Any idea?

Zael

154

March 23, 2012 04:46 PM

MinGW does not fully support C++11 features yet. This may be one of those items that isn't quite there.

Bregma

9,461

March 23, 2012 05:29 PM

That error means a failure to open the file "/dev/urandom". My guess is that such a device is not supported under MinGW. If there is in fact a valid hardware entropy source available in Windows and presented as a file node, pass the name of that to the std::random_device constructor, otherwise you will not be able to use the hardware entropy source feature of the standard library.

You could, instead, use good old std::time() to initialize your PRNG engine. It's pretty portable and good enough for non-cryptographic purposes.

Stephen M. Webb
Professional Free Software Developer

belfegor

2,836

Author

March 23, 2012 05:43 PM

Thanks. I thought it was somehow my fault.

@Bregma
Like this?



std::mt19937 gen(static_cast<unsigned int>(std::time(nullptr)));

...

Is this suitable for game projects puproses, when it is possibly called multiple times in "tight" loops?

alvaro

21,604

March 23, 2012 05:45 PM

Seeding a pseudo-random number generator in a tight loop is never a good option. You should seed it once and use it many times.

Mingw g++ 4.6.2 crash

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