JAVA，

JAVA，

package hello;

import java.util.InputMismatchException;
import java.util.Scanner;

public class Date {

static int date_input() {

	Scanner in = new Scanner(System.in);
	int date = 0;

	try {
		date = in.nextInt();
	} catch (InputMismatchException e) {
		System.out.println("输入有误\n请重新输入!");
		date_input();
	}

	return date;
}

public static void main(String[] args) {

	while (true) {

		System.out.println("请输入年:");
		int year = date_input();
		System.out.println("请输入月:");
		int month = date_input();

		if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
			System.out.println("31天");
		} 
		else if (month == 4 || month == 6 || month == 9 || month == 11) {
			System.out.println("30天");
		} 
		else if (month == 2) {
			if ((year % 400 == 0) || (year % 4 == 0 && year % 100 != 0)) {
				System.out.println("29天");
			} 
			else {
				System.out.println("28天");
			}
		}
	}
}

}