help with clock()

Hi,
I just want a program to be in an infinite loop but only do part of the code once a certain amount of time has elapsed.

I've tried using clock() but can't get it to work. Is the clock reset everytime in a while() loop?

Here's my code so far. I try to print the "duration" everytime through the loop but it's always 0.000000000.

Code:

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#include <time.h>

int i = 0;
clock_t start, finish, current;
double        duration;

int main(){


        start = clock();

        while(1){
        duration = (double) (current - start) / CLOCKS_PER_SEC;
        printf("Time elapsed = %.10f\n", duration);
       
        if (duration >= 5){
        printf("5 Seconds is UP\n");
        }
        }
        return 0;
       
}

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This is similar.