Calculate the elapsed time of particular block of code in C

Calculate the time of particular block of the code. This time used to validate the execution time of the program of particular block of code.

Example:

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

void elapsed_time_display(struct timeval *start, struct timeval *end, char *time_for)
{
    double elapsed = 0;

    elapsed = (end->tv_sec - start->tv_sec) +
                      ((end->tv_usec - start->tv_usec)/1000000.0);

    printf("\n\n\t\tVel Elapsed %s time in second = %f  second= %d Microsecond = %d \n",time_for, elapsed, (int)(end->tv_sec - start->tv_sec), (int)(end->tv_usec - start->tv_usec));

}

int main()
{
    struct timeval time_start, time_end;
    int i = 0;

    gettimeofday(&time_start,NULL);
    printf("Calculate printf time\n");
    gettimeofday(&time_end,NULL);

    elapsed_time_display(&time_start, &time_end, "printf");

    gettimeofday(&time_start,NULL);
    while(i < 10000000) {
        i++;
    }
    gettimeofday(&time_end,NULL);

    elapsed_time_display(&time_start, &time_end, "while");

    return 0;
}

Output:

Calculate printf time

                Vel Elapsed printf time in second = 0.000014  second= 0 Microsecond = 14

                Vel Elapsed while time in second = 0.023843  second= 0 Microsecond = 23843