How to calculate execution time of your C program

Here is a short C program that will calculate the time of 300 squares and 300 cube of i ( where i is 1,2,3........300 )

/* timer.c - simple example of timing a piece of code */ 
#include <stdio.h> 
#include <sys/types.h> 
#include <time.h> 
main() 
{ 
int i; 
time_t t1,t2; 
(void) time(&t1); 

for (i=1;i<=300;++i) 

     printf("%d %d %d\n",i, i*i, i*i*i);
   
   
   (void) time(&t2); 

   printf("\nTime to do 300 squares and cubes= %d seconds\n", (int) t2-t1); 

}

Here we have used function time(&t1) that will calculate the time before the execution 

of the loop and save its value at the address of t1 and another function time(&t2)

which saves time after the loop is executed. In printf statement we are printing the 

difference of two time which is the time in which the loop is executed . hence you can

use this technique to find out your program execution timing.

Note : don't forget to add library files before compiling your C program.