函数判断素数

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int Judge(int num) {
	int flag = 0;
	for (int i = 2; i < num; ++i) {
		if (num%i == 0) {
			flag = 1;
		}
	}
	return flag;
}
int main() {
	int num,flag;
	scanf("%d", &num);
	flag=Judge(num);
	if (flag == 0) {
		printf("是素数\n");
	}
	if (flag == 1) {
		printf("不是素数\n");
	}
	system("pause");
	return 0;
}