编程入门练习#02

2、将整数逆序输出

import java.util.Scanner;
public class Main{
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int num = in.nextInt();
		int result = 0;
		int digit;
		do
		{
			digit = num%10;
			num = num/10;
			result = result*10 + digit;
		}while(num>0);
		System.out.println(result);
	}
}

3、计算数的阶乘

import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        /*
        int result=1;
        while (num!=0)
        {
            result = result*num;
            num = num - 1;
        }
        System.out.println(result);
         */
//        int factor = 1;
//        int n = 1;
//        while (n<=num)
//        {
//            factor = factor*n;
//            n = n+1;
//        }
        int factor = 1;
        for(int i=1; i<=num; i++)
        {
            factor = factor*i;
        }
        System.out.println(factor);
    }
}

4、输出100以内的素数

public class Main {
    public static void main(String[] args) {
        for(int n=2; n<100; n++)
        {
            int isPrime=1;
            for(int i=2; i

public class Main {
    public static void main(String[] args) {
        for(int i=1; i<=9; i++)
        {
            for(int j=1; j<=i; j++)
            {
                System.out.print(j+"*"+i+"="+i*j+" ");
            }
            System.out.println();
        }
    }
}