练习10—素数判断

import java.util.Scanner;

public class Demo {
    public static boolean isPrime(int input) {
        int n = (int) Math.sqrt(input);
        if (input == 1 || input <= 0)
            System.out.println("error");
        for (int i = 2; i <= n; i++) {
            if (input % i == 0)
                return false;
        }
        return true;
    }

    public static void main(String[] args) {
        int input;
        Scanner user = new Scanner(System.in);
        System.out.print("please enter an integer:");
        input = user.nextInt();
        if (isPrime(input))
            System.out.println(input + " is prime");
        else
            System.out.println(input + " not prime");
    }
}

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int isPrime(int input)
{
    if (input == 1 || input <= 0)
    {
        printf("error");
        exit(0);
    }
    int n = sqrt(input);
    for (int i = 2; i <= n; i++) 
    {
        if (input % i == 0)
        {
            return 1; //若条件满足,能被其他数整除,不是素数
        }
    }
    return 0;
}

int main()
{
    int input, i;
    printf("please enter the data:");
    scanf("%d", &input);
    if (isPrime(input))
        printf("%d is prime", input);
    else
        printf("%d not prime", input);
    return 0;
}