素数_c语言素数判断程序

import java.util.Scanner;
public class number {
    public static void main(String[] args) {
            int i = 0;
            System.out.println("1.3-100 2.任意两数 3.最大十个和最小十个");
            Scanner sc = new Scanner(System.in);
            i = sc.nextInt();
            switch (i) {
            case 1:
                isprime();
                break;
            case 2:
                isprime1();
                break;
            case 3:
                isprime2();
                break;
            }
        }
 
        public static void isprime() {
            int n;
            int i = 2;
            int m = 0;
            for (n = 3; n >= 3 && n <= 100; n++) {
                int j = 0;
                if (n % 2 == 0)
                    j = 1;
                for (i = 2; i <= Math.sqrt(n); i++) {
                    if (n % i == 0)
                        j = 1;
                }
                if (j == 0) {
                    m++;
                    System.out.print(n + "\t");
                    if (m % 5 == 0)
                        System.out.println();
                }
            }
            System.out.println();
        }
 
        public static void isprime1() {
            System.out.println("请输入两个整数：");
            Scanner sc = new Scanner(System.in);
            int num1, num2;
            System.out.println("number1:");
            num1 = sc.nextInt();
            System.out.println("number2:");
            num2 = sc.nextInt();
            int n;
            int i = 2;
            int m = 0;
            for (n = num1; n >= num1 && n <= num2; n++) {
                int j = 0;
                if (n % 2 == 0)
                    j = 1;
                for (i = 2; i <= Math.sqrt(n); i++) {
                    if (n % i == 0)
                        j = 1;
                }
                if (j == 0) {
                    m++;
                    System.out.print(n + "\t");
                    if (m % 5 == 0)
                        System.out.println();
                }
            }
        }
 
        public static void isprime2() {
            Scanner sc = new Scanner(System.in);
            System.out.println("请输入两个整数：");
            int num1, num2;
            System.out.println("number1:");
            num1 = sc.nextInt();
            System.out.println("number2:");
            num2 = sc.nextInt();
            System.out.println("十个最小：");
            int n;
            int i = 2;
            int m = 0;
            int k = 0;
            int a[] = new int[100];
            for (n = num1; n >= num1 && n <= num2; n++) {
                int j = 0;
                 
                if (n % 2 == 0)
                    j = 1;
                for (i = 2; i <= Math.sqrt(n); i++) {
                    if (n % i == 0)
                        j = 1;
                }
                if (j == 0) {
                    m++;
                    a[m] = n;
                    if (m <= 10)
                        System.out.print(a[m] + "\t");
                }
            }
            System.out.println();
            System.out.println("十个最大：");
            for (k = m - 10; k <= m; k++) {
                System.out.print(a[k] + "\t");
            }
 
        }
    }