Detecting 64bit compile in C

Question

is there a C macro or some kind of way that i can check if my c program was compiled as 64bit or 32bit at compile time in C?

Compiler: GCC Operating systems that i n

Answer 1

Use a compiler-specific macro.

I don't know what architecture you are targeting, but since you don't specify it, I will assume run-of-the-mill Intel machines, so most likely you are interested in testing for Intel x86 and AMD64.

For example:

#if defined(__i386__)
// IA-32
#elif defined(__x86_64__)
// AMD64
#else
# error Unsupported architecture
#endif

However, I prefer putting these in the separate header and defining my own compiler-neutral macro.