C语言库difftime()函数

#include <stdio.h>
#include <time.h>

int main () {
   time_t start_t, end_t;
   double diff_t;

   printf("Starting of the program.../n");
   time(&start_t);

   printf("Sleeping for 5 seconds.../n");
   sleep(5);

   time(&end_t);
   diff_t = difftime(end_t, start_t);

   printf("Execution time = %f/n", diff_t);
   printf("Exiting of the program.../n");

   return(0);
}