/*
 * $ gcc -ocpu_time__clock_t cpu_time__clock_t.c; ./cpu_time__clock_t
 */
#include <stdio.h>
#include <time.h>
#include <unistd.h>

int main()
{
    volatile int i;
    clock_t time_start, time_end;
    double cpu_time_used;

    #ifdef sysconf
    fprintf(stdout, "Number of clock ticks per sec ``sysconf(_SC_CLK_TCK)'': %ld\n",sysconf(_SC_CLK_TCK));
    #endif
    fprintf(stdout, "Number of clock ticks per second measured by the clock function ``CLOCKS_PER_SEC'': %ld\n", CLOCKS_PER_SEC);
    time_start = clock();
    for (i=0; i<100000000; i++)
        ;
    time_end = clock();
    cpu_time_used = ((double) (time_end - time_start)) / CLOCKS_PER_SEC;
    fprintf(stdout, "CPU time used for %ld iterations: %f\n", i, cpu_time_used);
    return 0;
}