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extern "c" Question.

Started by Ancient Spirit Oct 24, 2005 at 11:08 AM 3 replies 450+ views

Original Post

Oct 24, 2005 at 11:08 AM

I have encountered this syntex latly... I don't know what that means, all i know is that i can combine ASM, FORTRAN and other function to a c++ header file with it... Can someone explain please? thanks in advance.

TDragon

Oct 24, 2005 at 11:11 AM

extern "C" {} is used to indicate that whatever lies within should be treated as C rather than C++. This changes things like name-mangling, making it possible to link C object code into your C++ program correctly.

Ancient Spirit

Oct 24, 2005 at 11:15 AM

and how do i link ASM functions or FORTRAN to it?

eviltwigflipper

Oct 24, 2005 at 11:38 AM

Since I don't know exactlly what you doing, but if your using c++/C you just embed your asm inside of a function. I don't believe you can do it with fortran though.

Example

int my_asm_function( void ) {    int a = 0;    _asm {       handle A with asm    }    return a;}[/SOURCE]

nmi

Oct 24, 2005 at 11:41 AM

Quote:
Original post by Ancient Spirit
and how do i link ASM functions or FORTRAN to it?

You can create an assembler file, assemble it (i.e. with nasm) to get an object file, then link that file to your application. (This also works with other languages like fortran.)
To be able to call the function you declare it like:
extern "C" void foo(int param);

Make sure that your assembler function uses the correct calling convention for your compiler.

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