建一个WPF文件，选择两个日期，使用if,else语句并判断两个日期的大小

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace com
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            First.Text = DateTime.Today.ToString();
            Second.Text = DateTime.Today.ToString();
        }
        private void Quit_Click(object sender, RoutedEventArgs e)
        {
            this.Close();
        }
        private void show(string exp, bool result)
        {
            info.Text += exp;
            info.Text += " : " + result.ToString();
            info.Text += "\r\n";
        }
        private int dateCompare(DateTime left, DateTime right)
        {
            int result;
            if (left.Year > right.Year)
                result = 1;
            else if (left.Year < right.Year)
                result = -1;
            else if (left.Month > right.Month)
                result = 1;
            else if (left.Month < right.Month)
                result = -1;
            else if (left.Day > right.Day)
                result = 1;
            else if (left.Day < right.Day)
                result = -1;
            else
                result = 0;
            return result;
        }
        private void Compare_Click(object sender, RoutedEventArgs e)
        {
            int ans = dateCompare(First.SelectedDate.Value, Second.SelectedDate.Value);
            info.Text = "";
            show("First==Second", ans == 0);
            show("First>Second", ans == 1);
            show("First<Second", ans == -1);
        }
    }
}

建一个WPF文件，使用swith语句进行字符串的转换

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace camm
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void Copy_Click(object sender, RoutedEventArgs e)
        {
            target.Text = "";
            string from = source.Text;
            for (int i = 0; i < from.Length; i++)
            {
                char current = from[i];
                CopyOne(current);
            }
        }
        private void CopyOne(char current)
        {
            switch (current)
            {
                case '<':
                    target.Text += "<:";
                    break;
                case '>':
                    target.Text += ">:";
                    break;
                case '&':
                    target.Text += "&:";
                    break;
                case '\"':
                    target.Text += "":";
                    break;
                case '\'':
                    target.Text += "':";
                    break;
                default:
                    target.Text += current;
                    break;