输入一串字符，分析字符串中出现了哪些字符，每个字符出现了多少次

出了个题目给GF做，自己也做一遍。
题目：
输入一串字符，分析字符串中出现了哪些字符，每个字符出现了多少次。
解答：
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace yanysQustion
{
 /// <summary>
 /// Form1 的摘要说明。
 /// </summary>
 public class Form1 : System.Windows.Forms.Form
 {
  private System.Windows.Forms.Label label1;
  private System.Windows.Forms.Label label2;
  private System.Windows.Forms.Button button1;
  private System.Windows.Forms.Button button2;
  private System.Windows.Forms.Button button3;
  private System.Windows.Forms.Label label4;
  private System.Windows.Forms.ColorDialog colorDialog1;
  private System.Windows.Forms.TextBox t_scr;
  public System.Windows.Forms.TextBox t_res;
  private System.Windows.Forms.Button button4;
  public System.Windows.Forms.Label msg;
  /// <summary>
  /// 必需的设计器变量。
  /// </summary>
  private System.ComponentModel.Container components = null;

  public Form1()
  {
   //
   // Windows 窗体设计器支持所必需的
   //
   InitializeComponent();

   //
   // TODO: 在 InitializeComponent 调用后添加任何构造函数代码
   //
  }

  /// <summary>
  /// 清理所有正在使用的资源。
  /// </summary>
  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    if (components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  #region Windows 窗体设计器生成的代码
  /// <summary>
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  /// </summary>
  private void InitializeComponent()
  {
   this.t_scr = new System.Windows.Forms.TextBox();
   this.label1 = new System.Windows.Forms.Label();
   this.label2 = new System.Windows.Forms.Label();
   this.button1 = new System.Windows.Forms.Button();
   this.t_res = new System.Windows.Forms.TextBox();
   this.msg = new System.Windows.Forms.Label();
   this.button2 = new System.Windows.Forms.Button();
   this.button3 = new System.Windows.Forms.Button();
   this.label4 = new System.Windows.Forms.Label();
   this.colorDialog1 = new System.Windows.Forms.ColorDialog();
   this.button4 = new System.Windows.Forms.Button();
   this.SuspendLayout();
   //
   // t_scr
   //
   this.t_scr.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
   this.t_scr.Location = new System.Drawing.Point(0, 24);
   this.t_scr.Multiline = true;
   this.t_scr.Name = "t_scr";
   this.t_scr.Size = new System.Drawing.Size(480, 72);
   this.t_scr.TabIndex = 0;
   this.t_scr.Text = "";
   //
   // label1
   //
   this.label1.Location = new System.Drawing.Point(8, 8);
   this.label1.Name = "label1";
   this.label1.Size = new System.Drawing.Size(128, 16);
   this.label1.TabIndex = 1;
   this.label1.Text = "输入一串字符：";
   //
   // label2
   //
   this.label2.Location = new System.Drawing.Point(0, 104);
   this.label2.Name = "label2";
   this.label2.Size = new System.Drawing.Size(100, 16);
   this.label2.TabIndex = 2;
   this.label2.Text = "字符解析：";
   //
   // button1
   //
   this.button1.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
   this.button1.Location = new System.Drawing.Point(144, 128);
   this.button1.Name = "button1";
   this.button1.TabIndex = 3;
   this.button1.Text = "解 析";
   this.button1.Click += new System.EventHandler(this.button1_Click);
   //
   // t_res
   //
   this.t_res.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
   this.t_res.Location = new System.Drawing.Point(0, 128);
   this.t_res.Multiline = true;
   this.t_res.Name = "t_res";
   this.t_res.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
   this.t_res.Size = new System.Drawing.Size(136, 224);
   this.t_res.TabIndex = 0;
   this.t_res.Text = "";
   //
   // msg
   //
   this.msg.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
   this.msg.ForeColor = System.Drawing.Color.Red;
   this.msg.Location = new System.Drawing.Point(224, 128);
   this.msg.Name = "msg";
   this.msg.Size = new System.Drawing.Size(256, 224);
   this.msg.TabIndex = 4;
   //
   // button2
   //
   this.button2.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
   this.button2.Location = new System.Drawing.Point(144, 208);
   this.button2.Name = "button2";
   this.button2.TabIndex = 3;
   this.button2.Text = "背景颜色";
   this.button2.Click += new System.EventHandler(this.button2_Click);
   //
   // button3
   //
   this.button3.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
   this.button3.Location = new System.Drawing.Point(144, 248);
   this.button3.Name = "button3";
   this.button3.TabIndex = 3;
   this.button3.Text = "字体颜色";
   this.button3.Click += new System.EventHandler(this.button3_Click);
   //
   // label4
   //
   this.label4.Location = new System.Drawing.Point(224, 112);
   this.label4.Name = "label4";
   this.label4.Size = new System.Drawing.Size(100, 16);
   this.label4.TabIndex = 5;
   this.label4.Text = "分析：";
   //
   // button4
   //
   this.button4.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
   this.button4.Location = new System.Drawing.Point(144, 168);
   this.button4.Name = "button4";
   this.button4.TabIndex = 3;
   this.button4.Text = "清 空";
   this.button4.Click += new System.EventHandler(this.button4_Click);
   //
   // Form1
   //
   this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
   this.ClientSize = new System.Drawing.Size(480, 357);
   this.Controls.Add(this.label4);
   this.Controls.Add(this.msg);
   this.Controls.Add(this.button1);
   this.Controls.Add(this.label2);
   this.Controls.Add(this.label1);
   this.Controls.Add(this.t_scr);
   this.Controls.Add(this.t_res);
   this.Controls.Add(this.button2);
   this.Controls.Add(this.button3);
   this.Controls.Add(this.button4);
   this.Name = "Form1";
   this.Text = "小y";
   this.ResumeLayout(false);

  }
  #endregion

  /// <summary>
  /// 应用程序的主入口点。
  /// </summary>
  [STAThread]
  static void Main()
  {
   Application.Run(new Form1());
  }
//背景颜色
  private void button2_Click(object sender, System.EventArgs e)
  {
   //让用户可以打开颜色控件并细调颜色
   colorDialog1.AllowFullOpen=true;
   //显示帮助按钮
   colorDialog1.ShowHelp=true;
   //打开颜色选择框并等待用户选颜色后点击“确定”
   if(colorDialog1.ShowDialog()==DialogResult.OK)
    t_res.BackColor=colorDialog1.Color;

  }
//字体颜色
  private void button3_Click(object sender, System.EventArgs e)
  {
   //不让用户细调颜色
   colorDialog1.AllowFullOpen=false;
   //显示帮助按钮
   colorDialog1.ShowHelp=true;
   //打开颜色选择框并等待用户选颜色后点击“确定”
   if(colorDialog1.ShowDialog()==DialogResult.OK)
    t_res.ForeColor=colorDialog1.Color;
  }
//解析
  private void button1_Click(object sender, System.EventArgs e)
  {
   //字符串不能为空
   if(t_scr.Text=="")
   {
    MessageBox.Show("请输入一串字符！");
    return;
   }
   TimeSpan t1=new TimeSpan(DateTime.Now.Ticks);
   string soruce=t_scr.Text;
   int strLen=soruce.Length;
   int realLen=0;
   string realStr="";
   for(int i=0;i<strLen;i++)
   {
    if(soruce.IndexOf(soruce[i],i)==soruce.LastIndexOf(soruce[i]))
     realStr+=soruce[i];
   }
   realLen=realStr.Length;
   t_res.Text=string.Empty;
   for(int i=0;i<realLen;i++)
    t_res.AppendText(realStr[i]+" 出现次数："+(soruce.Split(realStr[i]).Length-1)+"\r\n");
   TimeSpan t2=new TimeSpan(DateTime.Now.Ticks);
   TimeSpan ts=t2.Subtract(t1).Duration();
   msg.Text="原始字符串长度："+strLen+"\r\n"+
         "出现的非重复字符数："+realLen+"\r\n"+
                     "运行时间："+ts.Minutes+"分"+ts.Seconds+"秒"+ts.Milliseconds+"毫秒";

  }
//清空
  private void button4_Click(object sender, System.EventArgs e)
  {
   t_scr.Text=string.Empty;
   t_res.Text=string.Empty;
   msg.Text=string.Empty;
  }
 }
}