#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define TRUE 1
#define FALSE 0
typedef long Yesno;
Yesno is_prime(long n);
/* check for prime function prototype */
int main()
{
unsigned long p;
char ch;
while(1)
{
srand((unsigned)time(NULL));
for(;;)
{
p = rand();
if (is_prime(p)) break;
}
printf("%u is prime.\n", p);
puts("Do you want another one? (y or n)?");
do
{
ch = getchar();
}
while(ch != 'n' && ch != 'y');
if(ch == 'n')
break;
}
system("PAUSE");
return 0;
}
Yesno is_prime(long n)
{
long divisor;
if (n<=1) return FALSE;
for
(divisor = 2; divisor * divisor <= n; divisor++)
if (n % divisor == 0)
return FALSE;
return TRUE;
}
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