record how long it takes to run function in c code example

Example 1: run time in c

#include <time.h>
clock_t begin = clock();

/* here, do your time-consuming job */

clock_t end = clock();
double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
printf("%f\n", time_spent);

Example 2: get time to complete code c

clock_t begin = clock();

/* here, do your time-consuming job */

clock_t end = clock();
double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;