File.AppendText(String) 方法

public:
 static System::IO::StreamWriter ^ AppendText(System::String ^ path);

public static System.IO.StreamWriter AppendText (string path);

static member AppendText : string -> System.IO.StreamWriter

Public Shared Function AppendText (path As String) As StreamWriter

参数

返回

StreamWriter

一个流写入器，它将 UTF-8 编码文本追加到指定文件或新文件。A stream writer that appends UTF-8 encoded text to the specified file or to a new file.

例外

示例

下面的示例将文本追加到文件中。The following example appends text to a file. 如果文件不存在，则方法会创建一个新的文件。The method creates a new file if the file doesn't exist. 但是， temp 在驱动器 C 上指定的目录必须存在，此示例才能成功完成。However, the directory named temp on drive C must exist for the example to complete successfully.

using namespace System;
using namespace System::IO;

int main()
{
   String^ path = "c:\\temp\\MyTest.txt";
   
   // This text is added only once to the file.
   if (  !File::Exists( path ) )
   {
      // Create a file to write to.
      StreamWriter^ sw = File::CreateText( path );
      try
      {
         sw->WriteLine( "Hello" );
         sw->WriteLine( "And" );
         sw->WriteLine( "Welcome" );
      }
      finally
      {
         if ( sw )
            delete (IDisposable^)sw;
      }
   }
   
   // This text is always added, making the file longer over time
   // if it is not deleted.
   StreamWriter^ sw = File::AppendText( path );
   try
   {
      sw->WriteLine( "This" );
      sw->WriteLine( "is Extra" );
      sw->WriteLine( "Text" );
   }
   finally
   {
      if ( sw )
         delete (IDisposable^)sw;
   }
   
   // Open the file to read from.
   StreamReader^ sr = File::OpenText( path );
   try
   {
      String^ s = "";
      while ( s = sr->ReadLine() )
      {
         Console::WriteLine( s );
      }
   }
   finally
   {
      if ( sr )
         delete (IDisposable^)sr;
   }
}

using System;
using System.IO;

class Test
{
    public static void Main()
    {
        string path = @"c:\temp\MyTest.txt";
        // This text is added only once to the file.
        if (!File.Exists(path))
        {
            // Create a file to write to.
            using (StreamWriter sw = File.CreateText(path))
            {
                sw.WriteLine("Hello");
                sw.WriteLine("And");
                sw.WriteLine("Welcome");
            }	
        }

        // This text is always added, making the file longer over time
        // if it is not deleted.
        using (StreamWriter sw = File.AppendText(path))
        {
            sw.WriteLine("This");
            sw.WriteLine("is Extra");
            sw.WriteLine("Text");
        }	

        // Open the file to read from.
        using (StreamReader sr = File.OpenText(path))
        {
            string s = "";
            while ((s = sr.ReadLine()) != null)
            {
                Console.WriteLine(s);
            }
        }
    }
}

Imports System.IO

Public Class Test
  Public Shared Sub Main()
    Dim path As String = "c:\temp\MyTest.txt"

    ' This text is added only once to the file. 
    If Not File.Exists(path) Then
      ' Create a file to write to.
      Using sw As StreamWriter = File.CreateText(path)
        sw.WriteLine("Hello")
        sw.WriteLine("And")
        sw.WriteLine("Welcome")
      End Using
    End If

    ' This text is always added, making the file longer over time 
    ' if it is not deleted.
    Using sw As StreamWriter = File.AppendText(path)
      sw.WriteLine("This")
      sw.WriteLine("is Extra")
      sw.WriteLine("Text")
    End Using

    ' Open the file to read from. 
    Using sr As StreamReader = File.OpenText(path)
      Do While sr.Peek() >= 0
        Console.WriteLine(sr.ReadLine())
      Loop
    End Using

  End Sub
End Class

注解

此方法等效于 StreamWriter(String, Boolean) 构造函数重载。This method is equivalent to the StreamWriter(String, Boolean) constructor overload. 如果指定的文件 path 不存在，则创建该文件。If the file specified by path does not exist, it is created. 如果文件存在，则将操作写入到 StreamWriter 文件中。If the file does exist, write operations to the StreamWriter append text to the file. 允许其他线程在文件打开时读取该文件。Additional threads are permitted to read the file while it is open.

path允许参数指定相对或绝对路径信息。The path parameter is permitted to specify relative or absolute path information. 相对路径信息被解释为相对于当前工作目录。Relative path information is interpreted as relative to the current working directory. 若要获取当前工作目录，请参见 GetCurrentDirectory 。To obtain the current working directory, see GetCurrentDirectory.

path参数不区分大小写。The path parameter is not case-sensitive.

有关常见 i/o 任务的列表，请参阅 常见 I/o 任务。For a list of common I/O tasks, see Common I/O Tasks.

适用于

另请参阅

• StreamWriter
• 文件和流 I/OFile and Stream I/O
• 从文件读取文本Reading Text From A File
• 如何：将文本写入文件How to: Write Text to a File
• 如何：对新建的数据文件进行读取和写入How to: Read and Write to a Newly Created Data File