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:

#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;
	
}

This is similar.