问题:：在执行了button1_Click，在满足if的条件下，richTextBox4无输出。请大家指点下，谢谢！

using System;
using System.Collections.Generic;
.....
namespace InfoSearch
{
    public partial class Form1 : Form
    {
           public Form1()
        {
            InitializeComponent();
         
        }
    private void button1_Click(object sender, EventArgs e)        
       {
         
            char[] Name = richTextBox1.Text.ToCharArray();
            string a = Name[0].ToString();
            string b = richTextBox2.Text.Trim();
            string c = richTextBox3.Text.Trim();
            string r1 = "";
            string r2 = "";
            richTextBox4.Text = r1.ToString() + r2.ToString();//输出if的结果

            if ((a == "北" || a == "上") && (b == "地铁" || b == "公交"))
            {
                r1 = "拥堵";
            }
            else
                r1 = "";
            if ((a == "成" || a == "西") && (b == "铁路" || b == "飞机"))
            {
                r1 = "少量";
            }
            else
                r1 = "";
           if ((c == "游客" || c == "背包客") && (b == "铁路" || b == "飞机"))
            {
                r2 = "增加中";
            }
            else
                r2 = "";

           }
    }
}

将“richTextBox4.Text = ...”放在最后也还是没有输出

是的  真牛！
追问下： 对于 richTextBox4.Text = r1 + " " + r2;//需要在2个值之间添加1个空格。如果r1的值为空，richTextBox4.Text 只显示r2,而不是" "r2。是要怎么来进行判断呢？