Like time, but more accurate

clock.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <time.h>

#ifndef __unix__
#error only supports unix!
#endif // __unix__

#include <unistd.h>

double ExecuteAC(char** argv){
  pid_t pid=fork();
  if(pid==0){
    // child process
    execv(argv[0], argv);
    exit(127);
  }else{
    // parent process
    long before=clock();
    waitpid(pid, 0, 0);
    long after=clock();
    return (double) (after-before)/CLOCKS_PER_SEC;
  }
}

int main(int argc, char** argv){
  if(argc<2){
    printf("Usage: %s <filenm>", argv[0]);
    return 0;
  }

  printf("Time: %lf", ExecuteAC(argv+1));

  return 0;
}