clock() function in c with example program

 To calculate the time in c programming we can use clock() function in c which is define in time.h header file clock  can call at the beginning and end of the code for which will help to measure time.

In this process subtract the obtain values for the clock function, and then divide by CLOCKS_PER_SEC (the number of clock ticks per second)to get time.

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Syntax for clock function in c

 #include <time.h>
     
     clock_t start, end;
     double cpu_time_used;
     
     start = clock();
     ... /* Do the work. */
     end = clock();
     cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;

Following C program will tell how to measure time with the help of clock() function in c and we also use fun() function which will help to terminate the process after enter key press to terminate.

Example program for clock() function in c

/* Program to demonstrate time taken by function fun() */

#include <stdio.h>

#include <time.h>

  

// A function that terminates when enter key is pressed

void fun()

{

    printf("fun() starts \n");

    printf("Press enter to stop fun \n");

    while(1)

    {

        if (getchar())

            break;

    }

    printf("fun() ends \n");

}

  

// The main program calls fun() and measures time taken by fun()

int main()

{

    // Calculate the time taken by fun()

    clock_t t;

    t = clock();

    fun();

    t = clock() - t;

    double time_taken = ((double)t)/CLOCKS_PER_SEC; // in seconds

  

    printf("fun() took %f seconds to execute \n", time_taken);

    return 0;

}

OUTPUT :- 

clock function in c