CODEWITHSUNDEEP
ubuntuctime
Goktug
Goktug

Reputation: 923

Sleep and Clock Method

int main(void){

    int start = clock();
    sleep(5);
    int end = clock();

    printf("%d", (end - start));
    return 0;
}

When I execute this code in ubuntu, I get the result 30; however, I suspend the process in 5 seconds by sleep() method. Why is the result equal to 30 ?

How can I compute suspended time of the process ?

Upvotes: 0

Views: 27

Answers (1)

Kusalananda
Kusalananda

Reputation: 15603

The clock() function returns the amount of CPU time used since the process started. To get the number in seconds, you should divide by the constant CLOCKS_PER_SEC.

In most cases, no or very little CPU time will be used in a call to sleep (I always get zero back).

You could use time() to get seconds of wall clock time:

#include <stdio.h>
#include <time.h>
#include <unistd.h>

int main(void) {

  time_t start = time(NULL);
  sleep(5);
  time_t end = time(NULL);

  printf("%.1f\n", difftime(end, start));

  return 0;
}

For timing short intervals gettimeofday() may be more useful as it gives microsecond granularity instead of just seconds, like time().

Upvotes: 3

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