C#文件基本操作3-文本数据写入读出演示

 1 using System;
 2 using System.Collections.Generic;
 3 using System.ComponentModel;
 4 using System.Data;
 5 using System.Drawing;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Threading.Tasks;
 9 using System.Windows.Forms;
10 using System.IO;
11 
12 namespace WindowsFormsApplication1
13 {
14     public partial class Form1 : Form
15     {
16         public Form1()
17         {
18             InitializeComponent();
19         }
20 
21         private void button1_Click(object sender, EventArgs e)
22         {
23             if (textBox1.Text == string.Empty)
24             {
25                 MessageBox.Show("empty");
26             }
27             else
28             {
29                 saveFileDialog1.Filter = "text file(*.txt)|*.txt";
30                 if (saveFileDialog1.ShowDialog() == DialogResult.OK)
31                 {
32                     StreamWriter sw = new StreamWriter(saveFileDialog1.FileName, true);
33                     sw.WriteLine(textBox1.Text);
34                     sw.Close();
35                     textBox1.Text = string.Empty;
36                 }
37             }
38         }
39 
40         private void button2_Click(object sender, EventArgs e)
41         {
42             openFileDialog1.Filter = " textfile(*.txt)|*.txt";
43             if (openFileDialog1.ShowDialog() == DialogResult.OK)
44             {
45                 textBox1.Text = string.Empty;
46                 StreamReader sr = new StreamReader(openFileDialog1.FileName);
47                 textBox1.Text = sr.ReadToEnd();
48                 sr.Close();
49             }
50         }
51     }
52 }