clock() function does not work.

Question

This code should print internal time every second. But it does not work. Why?

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

int main()
{
    long int lastTime=clock();
    while(1==1){
        if (lastTime < clock()-1000){ 
            lastTime = clock();
            printf ("internal clock = %d\n", clock());
        }
    }    return 0;
}

Answer 1

The clock() function does not return time in milliseconds, as you assumed. To get the time measured in milliseconds, you need to divide the returned value by CLOCKS_PER_SEC.

I've fixed up your code and added some improvements:

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

int main()
{
    clock_t nextTick = clock() + CLOCKS_PER_SEC;
    while (1)
    {
        clock_t timeNow = clock();
        if (nextTick <= timeNow)
        { 
            nextTick += CLOCKS_PER_SEC;
            printf("internal clock = %ld\n", timeNow);
        }
    }
    return 0;
}

Comments

Thanks a lot!

Answer 2

Hello, this is Gulshan Negi

Well, there are some issue with print function, here is the correct code: 

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

int main()
{
    long int lastTime = time(NULL); // Get the current time in seconds since the epoch
    while (1) {
        if (lastTime < time(NULL) - 1) { // Compare the current time with lastTime + 1 second
            lastTime = time(NULL); // Update lastTime with the new current time
            printf("Internal time = %ld\n", lastTime);
        }
    }
    return 0;
}

Thanks

Comments

Your code does not print the time every second as the poster wanted to.

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Well, is it working find ?