File.AppendText(String) File.AppendText(String) File.AppendText(String) File.AppendText(String) Method

Definition

Creates a StreamWriter that appends UTF-8 encoded text to an existing file, or to a new file if the specified file does not exist.

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

Parameters

path
String String String String

The path to the file to append to.

Returns

A stream writer that appends UTF-8 encoded text to the specified file or to a new file.

Exceptions

path is a zero-length string, contains only white space, or contains one or more invalid characters as defined by InvalidPathChars.

The specified path, file name, or both exceed the system-defined maximum length.

The specified path is invalid (for example, the directory doesn't exist or it is on an unmapped drive).

Examples

The following example appends text to a file. The method creates a new file if the file doesn't exist. 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

Remarks

This method is equivalent to the StreamWriter(String, Boolean) constructor overload. If the file specified by path does not exist, it is created. If the file does exist, write operations to the StreamWriter append text to the file. Additional threads are permitted to read the file while it is open.

The path parameter is permitted to specify relative or absolute path information. Relative path information is interpreted as relative to the current working directory. To obtain the current working directory, see GetCurrentDirectory.

The path parameter is not case-sensitive.

For a list of common I/O tasks, see Common I/O Tasks.

Security

FileIOPermission
for appending to the specified file. Associated enumeration: Append

Applies to

See also