#include <stdio.h>
/* A function to test if a number is prime, takes an integer and returns a
* boolean. (We'll just use an int for the boolean)
*/
int isPrime(int n) {
int i;
if (n < 2) {
return 0;
}
/* Try dividing by all numbers from 2 to sqrt(n). */
for (i = 2; i*i <= n; ++i) {
if (n % i == 0) {
return 0;
}
}
/* If we get here, we didn't find a factor, so n is prime. */
return 1;
}
int main(void) {
char name[100];
int number;
printf("What is your name? (one word only please) ");
scanf("%s", name);
printf("Hello, %s!\n", name);
printf("What is your favorite number? ");
scanf("%d", &number);
printf("Your favorite number is %d", number);
if (isPrime(number)) {
printf(", and that's a prime number!\n");
} else {
printf(". It's not a prime number, but that's okay!\n");
}
return 0;
}
