C clock() function

C clock() function - Report CPU time used

The clock() function is used to get the processor time used by the process since the beginning of an implementation-defined era related only to the process invocation.

Syntax:

clock_t clock(void)

Parameters:

Not available

Return value from clock() function

• If the value of the processor time is not available or cannot be represented, the clock() function returns the value (clock_t)-1.

Example: clock() function

Following function prints the time that has elapsed since the program was invoked:

#include <time.h>
#include <stdio.h>
 
double time1, time_diff;   
 
int main(void)
{
    int n;
 
    time1 = (double) clock();  // get initial time 
    time1 = time1 / CLOCKS_PER_SEC;  // in seconds
 
    /* Running the FOR loop 100000000 times */
    for (n=0; n<100000000; n++);
 
    /* call clock a second time */
    time_diff = (((double) clock()) / CLOCKS_PER_SEC) - time1;
    printf("The elapsed time is %lf seconds\n", time_diff);
}

Output:

The elapsed time is 0.144000 seconds

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