判断一个数是否为素数
思路:若一个数n不能被2和√n之间的数整除(即取模为0),则可判断n为素数。可从2开始测试,一直到√n为止。(for循环)
代码如下:
#include<iostream>using namespace std;#include<string>#include<cmath>void is_prime(int num){int dex = sqrt(num);bool out = 1;if (num == 2 || num == 3)cout << num << "是素数" << endl;else if (num == 0 || num == 1)cout << num << "不是素数" << endl;else {for (int i = 2; i <= dex; i++){if (num % i == 0){out = 0;break;}}if (out){cout << num << "是素数" << endl;}else{cout << num << "不是素数" << endl;}}}int main(){int num;int n;cout << "请输入要测试的个数:" << endl;cin >> n;for (int i = 0; i < n; i++){cout << "请输入一个整数:" << endl;cin >> num;is_prime(num);system("pause");//设置暂停方便观察system("cls");//设置清屏}return 0;}