/* clock example: frequency of primes */
#include <stdio.h> /* printf */
#include <time.h> /* clock_t, clock, CLOCKS_PER_SEC */
#include <math.h> /* sqrt */
int frequency_of_primes (int n) {
int i,j;
int freq=n-1;
for (i
=2; i
<=n
; ++i
) for (j
=sqrt(i
);j
>1;--j
) if (i
%j
==0) {--freq
; break;} return freq;
}
int main ()
{
clock_t t;
int f;
f = frequency_of_primes (99999);
printf ("The number of primes lower than 100,000 is: %d\n",f
); float diff = ((float)t)/CLOCKS_PER_SEC;
printf ("It took me %d clicks (%f milliseconds).\n",t
,diff
*1000); return 0;
}
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