using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections;

namespace 上寨微博
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        Hashtable table = new Hashtable();
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            table.Clear();//这里不懂?

            //1.检查个数
            string str = textBox1.Text.Trim();
            int num = str.Length;
            int numTotal = 140;
            int dif = numTotal - num;
            //2.统计个数
            for (int i = 0; i < str.Length; i++)
            {
                //看看这个字符串在集合中是否存在，如果存在个数加一
                //不存在，将其加进去，将个数初始化为1
                string current = str[i].ToString();
                if (table.ContainsKey(current))
                {
                    //存在
                    int numTemp = Convert.ToInt32(table[current]);
                    table[current] = numTemp + 1;
                }
                else
                {
                    //不存在
                    table.Add(current, 1);
                }
            }
            //3.显示统计结果与总数
            StringBuilder sb = new StringBuilder();
            foreach (DictionaryEntry item in table)
            {
                sb.AppendFormat("汉字{0},出现{1}\r\n",item.Key,item.Value);
            }
            label1.Text = sb.ToString();
            //4.考虑按钮是否可用
            label2.Text = dif.ToString();

            if (dif<0)
            {
                button1.Enabled = false;
            }
            else
            {
                button1.Enabled = true;
            }
        }
    }
}

请问这里table.Clear()是什么意思

原来如此，多谢多谢