Some issues in C runtime calculation

use time.h

The clock() function has limitation in terms of the maximum value returned

on a 32 bit machine it overflows at around 36 minutes

use time() function instead.

Time returns no of seconds since epoch.

time_t start, end;

time(&start);

/*Do Something*/

time(&end);

printf("Runtime in seconds %d\n", (int)end-start);