execres.c

/******************
* File: execres.c *
******************/

#include "execres.h"
#include <stdlib.h>

PExecResult execTime( void* (*code)( void*), void* param ){
    PExecResult result = (PExecResult) malloc( sizeof(ExecResult) );

#ifdef __GNUC__
    struct timeval tva;
    struct timeval tvb;
#elif defined _MSC_VER
    DWORD dwa;
    DWORD dwb;
#endif

    if( result == NULL || code == NULL ) return NULL;

#ifdef __GNUC__
    gettimeofday( &tva, NULL );
    result->result = code( param );
    gettimeofday( &tvb, NULL );

    result->millis = (unsigned long long)(
            tvb.tv_sec * 1000 + tvb.tv_usec / 1000 -
            tva.tv_sec * 1000 - tva.tv_usec / 1000
            );

#elif defined _MSC_VER
    dwa = GetTickCount();
    result->result = code( param );
    dwb = GetTickCount();

    result->millis = (unsigned long long)( dwb - dwa );
#endif

    return result;
}

execres.h

/******************
* File: execres.h *
******************/

#ifndef EXECRES_H
#define EXECRES_H

#ifdef __GNUC__
#   include <sys/time.h>
#else
#   error Environment not supported.
#endif

typedef struct {
    unsigned long long  millis;
    void*               result;
} ExecResult, *PExecResult;

PExecResult execTime(void* (*code)(void*), void* param);

#endif  /* EXECRES_H */

main.c

/***************
* File: main.c *
***************/

#include <stdint.h>
#include <stdio.h>
#include "execres.h"

static uint64_t Fibonacci(uint64_t n) 
{
    switch (n)
    {
        case 0:
            return 0;
            
        case 1:
            return 1;
            
        default:
            return Fibonacci(n - 1) + Fibonacci(n - 2);
    }
}

int main() {
    PExecResult result = execTime((void* (*)(void*)) Fibonacci, (void*) 40);

    printf("Fibonacci took %u milliseconds and returned %llu.",
            (unsigned) result->millis,
            (uint64_t) result->result);

    getchar();
    return 0;
}