在 Visual C 中执行基本文件 I/O# - C#

演示的文件 I/O 操作

本文中的示例介绍了基本的文件 I/O 操作。分步示例部分介绍如何创建演示以下文件 I/O 操作的示例程序：
读取文本文件
编写文本文件
查看文件信息
列出磁盘驱动器
列出文件夹
如果要直接使用以下代码示例，请注意以下事项：
System.IO 包括命名空间，如下所示：
using System.IO;
winDir按如下所示声明变量：
string winDir=System.Environment.GetEnvironmentVariable("windir");
函数 addListItem 的声明如下：
private void addListItem(string value)
    this.listBox1.Items.Add(value);
可以直接使用以下 addListItem 语句，而不是声明和使用 函数：
this.listBox1.Items.Add(value);
读取文本文件
下面的示例代码使用 StreamReader 类读取 System.ini 文件。 文件的内容将添加到 ListBox 控件。 块 try...catch 用于在文件为空时向程序发出警报。 有多种方法可以确定何时到达文件末尾;此示例使用 Peek 方法在阅读前检查下一行。
StreamReader reader=new StreamReader(winDir + "\\system.ini");
        addListItem(reader.ReadLine());
    while(reader.Peek()!= -1);
catch
    addListItem("File is empty");
finally
    reader.Close();
编写文本文件
此示例代码使用 StreamWriter 类创建和写入文件。 如果有现有文件，则可以以相同方式打开它。
StreamWriter writer = new StreamWriter("c:\\KBTest.txt");
writer.WriteLine("File created using StreamWriter class.");
writer.Close();
this.listbox1.Items.Clear();
addListItem("File Written to C:\\KBTest.txt");
查看文件信息
此示例代码使用 FileInfo 对象访问文件的属性。 此示例使用 Notepad.exe。 属性显示在 ListBox 控件中。
FileInfo FileProps =new FileInfo(winDir + "\\notepad.exe");
addListItem("File Name = " + FileProps.FullName);
addListItem("Creation Time = " + FileProps.CreationTime);
addListItem("Last Access Time = " + FileProps.LastAccessTime);
addListItem("Last Write TIme = " + FileProps.LastWriteTime);
addListItem("Size = " + FileProps.Length);
FileProps = null;
列出磁盘驱动器
此示例代码使用 Directory 和 Drive 类列出系统上的逻辑驱动器。 对于此示例，结果显示在 ListBox 控件中。
string[] drives = Directory.GetLogicalDrives();
foreach(string drive in drives)
    addListItem(drive);
列出子文件夹
此示例代码使用 GetDirectories 类的 Directory 方法来获取文件夹列表。
string[] dirs = Directory.GetDirectories(winDir);
foreach(string dir in dirs)
    addListItem(dir);
此示例代码使用 GetFiles 类的 Directory 方法来获取文件列表。
string[] files= Directory.GetFiles(winDir);
foreach (string i in files)
    addListItem(i);
当用户获得对文件的访问权限时，许多事情都可能会出错。 这些文件可能不存在，文件可能正在使用中，或者用户可能没有他们尝试访问的文件或文件夹的权限。 在编写代码和处理可能生成的异常时，请务必考虑这些可能性。
在 Visual C# 中，创建新的Windows 窗体应用程序。 默认情况下， 将创建 Form1 。
打开 Form1 (Form1.cs)  的代码窗口。
删除 Form1.cs中的所有代码。
将以下代码粘贴到“代码隐藏编辑器”窗口中。
using System.Windows.Forms;
using System.IO;
namespace fso_cs
    public partial class Form1 : Form
        string winDir = System.Environment.GetEnvironmentVariable("windir");
        public Form1()
            InitializeComponent();
        private void button1_Click(object sender, System.EventArgs e)
            //How to read a text file.
            //try...catch is to deal with a 0 byte file.
            this.listBox1.Items.Clear();
            StreamReader reader = new StreamReader(winDir + "\\system.ini");
                    addListItem(reader.ReadLine());
                while (reader.Peek()!= -1);
            catch
                addListItem("File is empty");
            finally
                reader.Close();
        private void button2_Click(object sender, System.EventArgs e)
            //Demonstrates how to create and write to a text file.
            StreamWriter writer = new StreamWriter("c:\\KBTest.txt");
            writer.WriteLine("File created using StreamWriter class.");
            writer.Close();
            this.listBox1.Items.Clear();
            addListItem("File Written to C:\\KBTest.txt");
        private void button3_Click(object sender, System.EventArgs e)
            //How to retrieve file properties (example uses Notepad.exe).
            this.listBox1.Items.Clear();
            FileInfo FileProps = new FileInfo(winDir + "\\notepad.exe");
            addListItem("File Name = " + FileProps.FullName);
            addListItem("Creation Time = " + FileProps.CreationTime);
            addListItem("Last Access Time = " + FileProps.LastAccessTime);
            addListItem("Last Write TIme = " + FileProps.LastWriteTime);
            addListItem("Size = " + FileProps.Length);
            FileProps = null;
        private void button4_Click(object sender, System.EventArgs e)
            //Demonstrates how to obtain a list of disk drives.
            this.listBox1.Items.Clear();
            string[] drives = Directory.GetLogicalDrives();
            foreach (string drive in drives)
                addListItem(drive);
        private void button5_Click(object sender, System.EventArgs e)
            //How to get a list of folders (example uses Windows folder). 
            this.listBox1.Items.Clear();
            string[] dirs = Directory.GetDirectories(winDir);
            foreach (string dir in dirs)
                addListItem(dir);
        private void button6_Click(object sender, System.EventArgs e)
            //How to obtain list of files (example uses Windows folder).
            this.listBox1.Items.Clear();
            string[] files = Directory.GetFiles(winDir);
            foreach (string i in files)
                addListItem(i);
        private void Form1_Load(object sender, System.EventArgs e)
            this.button1.Text = "Read Text File";
            this.button2.Text = "Write Text File";
            this.button3.Text = "View File Information";
            this.button4.Text = "List Drives";
            this.button5.Text = "List Subfolders";
            this.button6.Text = "List Files";
        private void addListItem(string value)
            this.listBox1.Items.Add(value);
打开 Form1.Designer 的代码窗口。cs.
删除 Form1.Designer 中的所有代码。cs.
将以下代码粘贴到 Form1.Designer 中。cs.
namespace fso_cs
    partial class Form1
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;
        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
            if (disposing && (components != null))
                components.Dispose();
            base.Dispose(disposing);
        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
            this.button1 = new System.Windows.Forms.Button();
            this.button2 = new System.Windows.Forms.Button();
            this.button3 = new System.Windows.Forms.Button();
            this.button4 = new System.Windows.Forms.Button();
            this.button5 = new System.Windows.Forms.Button();
            this.button6 = new System.Windows.Forms.Button();
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.SuspendLayout();
            // button1
            this.button1.Location = new System.Drawing.Point(53, 30);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(112, 23);
            this.button1.TabIndex = 1;
            this.button1.Text = "button1";
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // button2
            this.button2.Location = new System.Drawing.Point(53, 62);
            this.button2.Name = "button2";
            this.button2.Size = new System.Drawing.Size(112, 23);
            this.button2.TabIndex = 2;
            this.button2.Text = "button2";
            this.button2.Click += new System.EventHandler(this.button2_Click);
            // button3
            this.button3.Location = new System.Drawing.Point(53, 94);
            this.button3.Name = "button3";
            this.button3.Size = new System.Drawing.Size(112, 23);
            this.button3.TabIndex = 3;
            this.button3.Text = "button3";
            this.button3.Click += new System.EventHandler(this.button3_Click);
            // button4
            this.button4.Location = new System.Drawing.Point(53, 126);
            this.button4.Name = "button4";
            this.button4.Size = new System.Drawing.Size(112, 23);
            this.button4.TabIndex = 4;
            this.button4.Text = "button4";
            this.button4.Click += new System.EventHandler(this.button4_Click);
            // button5
            this.button5.Location = new System.Drawing.Point(53, 158);
            this.button5.Name = "button5";
            this.button5.Size = new System.Drawing.Size(112, 23);
            this.button5.TabIndex = 5;
            this.button5.Text = "button5";
            this.button5.Click += new System.EventHandler(this.button5_Click);
            // button6
            this.button6.Location = new System.Drawing.Point(53, 190);
            this.button6.Name = "button6";
            this.button6.Size = new System.Drawing.Size(112, 23);
            this.button6.TabIndex = 6;
            this.button6.Text = "button6";
            this.button6.Click += new System.EventHandler(this.button6_Click);
            // listBox1
            this.listBox1.FormattingEnabled = true;
            this.listBox1.Location = new System.Drawing.Point(204, 30);
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(270, 199);
            this.listBox1.TabIndex = 7;
            // Form1
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(525, 273);
            this.Controls.Add(this.button6);
            this.Controls.Add(this.button5);
            this.Controls.Add(this.button4);
            this.Controls.Add(this.button3);
            this.Controls.Add(this.button2);
            this.Controls.Add(this.button1);
            this.Controls.Add(this.listBox1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.ResumeLayout(false);
        #endregion
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.Button button2;
        private System.Windows.Forms.Button button3;
        private System.Windows.Forms.Button button4;
        private System.Windows.Forms.Button button5;
        private System.Windows.Forms.Button button6;
        private System.Windows.Forms.ListBox listBox1;
默认情况下，在创建Windows 窗体项目时，Visual C# 会向项目添加一个窗体。 此窗体名为 Form1。 表示表单的两个源代码文件名为 Form1.cs 和 Form1.Designer。cs. 在 Form1.cs 文件中编写代码。 Windows 窗体 Designer在 Form1.Designer 中编写设计器生成的代码。cs 文件。 上述步骤中的代码反映了该组织。
按 F5 生成，然后运行程序。 单击按钮可查看不同的操作。 查看示例代码时，可能需要折叠名为“Windows 窗体”Designer“生成代码”的区域来隐藏此代码。
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