C# 文本文件的查找及替换(WinForm)

using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.IO;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;namespace SupperReplace
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
             openFileDialog1.AddExtension = true;
             openFileDialog1.DefaultExt = "txt";
             openFileDialog1.Filter = @"*.txt|*.txt";
         }        private void btnSelectFile_Click(object sender, EventArgs e)
         {
             if (openFileDialog1.ShowDialog() == DialogResult.OK)
             {
                 txtBoxFile.Text = openFileDialog1.FileName;
             }
         }        private void btnSearch_Click(object sender, EventArgs e)
         {
             string search = txtBoxSearch.Text.Trim();
             if (!string.IsNullOrEmpty(search))
             {
                 string fileName = txtBoxFile.Text.Trim();
                 using (TextReader tr = File.OpenText(fileName))
                 {
                     string content = tr.ReadToEnd();
                     int count = CountNumber(content, search);
                     DisplaySearchCount(count);
                 }
             }
         }        void DisplaySearchCount(int count)
         {
             lblSearchResult.Text = "共查找到:\r\n" + count.ToString() + "\r\n个结果。";
         }        void DisplayReplaceCount(int count)
         {
             DisplaySearchCount(count);
             lblReplaceResult.Text = "共查找到:\r\n" + count.ToString() + "\r\n个结果。";
         }         private int CountNumber(string father, string son)
         {
             //判断是否有相同字符串
             if (father.Contains(son))
             {
                 //用一个字符串储存被替换后的整个字符串
                 string strReplaced = father.Replace(son, "");
                 //两个字符串的长度差值 / 被替换掉的字符串单位长度
                 return (father.Length - strReplaced.Length) / son.Length;
             }
             //没有返回0个
             return 0;
         }        private void btnReplace_Click(object sender, EventArgs e)
         {
             string search = txtBoxSearch.Text;
             string replace = txtBoxReplace.Text;
             if (!string.IsNullOrEmpty(search))
             {
                 string fileName = txtBoxFile.Text.Trim();
                 string content, result;
                 using (TextReader tr = File.OpenText(fileName))
                 {
                     content = tr.ReadToEnd();
                     result = content.Replace(search, replace);                }
                 //写入文件
                 using (FileStream fs = File.Open(fileName, FileMode.Create, FileAccess.Write, FileShare.None))
                 {
                     Byte[] info = new UTF8Encoding(true).GetBytes(result);
                     fs.Write(info, 0, info.Length);
                 }
                 int count = CountNumber(content, search);
                 DisplayReplaceCount(count);
             }
         }
     }
 }