Can I compute pow(10,x) at compile-time in c?

There are very few values possible before you overflow int (or even long). For clarities sake, make it a table!

edit: If you are using floats (looks like you are), then no it's not going to be possible to call the pow() function at compile time without actually writing code that runs in the make process and outputs the values to a file (such as a header file) which is then compiled.

GCC will do this at a sufficiently high optimization level (-O1 does it for me). For example:

#include <math.h>

int test() {
        double x = pow(10, 4);
        return (int)x;
}

Compiles at -O1 -m32 to:

        .file   "test.c"
        .text
.globl test
        .type   test, @function
test:
        pushl   %ebp
        movl    %esp, %ebp
        movl    $10000, %eax
        popl    %ebp
        ret
        .size   test, .-test
        .ident  "GCC: (Ubuntu 4.3.3-5ubuntu4) 4.3.3"
        .section        .note.GNU-stack,"",@progbits

This works without the cast as well - of course, you do get a floating-point load instruction in there, as the Linux ABI passes floating point return values in FPU registers.

You can do it with Boost.Preprocessor:

http://www.boost.org/doc/libs/1_39_0/libs/preprocessor/doc/index.html

Code:

#include <boost/preprocessor/repeat.hpp>

#define _TIMES_10(z, n, data) * 10
#define POW_10(n) (1 BOOST_PP_REPEAT(n, _TIMES_10, _))

int test[4] = {POW_10(0), POW_10(1), POW_10(2), POW_10(3)};