File.AppendAllText File.AppendAllText File.AppendAllText File.AppendAllText Method

Definition

Appends the specified stringto the file, creating the file if it does not already exist.

Overloads

AppendAllText(String, String) AppendAllText(String, String) AppendAllText(String, String) AppendAllText(String, String)

Opens a file, appends the specified string to the file, and then closes the file. If the file does not exist, this method creates a file, writes the specified string to the file, then closes the file.

AppendAllText(String, String, Encoding) AppendAllText(String, String, Encoding) AppendAllText(String, String, Encoding)

Appends the specified string to the file, creating the file if it does not already exist.

AppendAllText(String, String) AppendAllText(String, String) AppendAllText(String, String) AppendAllText(String, String)

Opens a file, appends the specified string to the file, and then closes the file. If the file does not exist, this method creates a file, writes the specified string to the file, then closes the file.

public:
 static void AppendAllText(System::String ^ path, System::String ^ contents);
public static void AppendAllText (string path, string contents);
static member AppendAllText : string * string -> unit
Public Shared Sub AppendAllText (path As String, contents As String)
Parameters
path
String String String String

The file to append the specified string to.

contents
String String String String

The string to append to the 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).

An I/O error occurred while opening the file.

path specified a file that is read-only.

-or-

This operation is not supported on the current platform.

-or-

path specified a directory.

-or-

The caller does not have the required permission.

The caller does not have the required permission.

Examples

The following code example demonstrates the use of the AppendAllText method to add extra text to the end of a file. In this example, a file is created if it doesn't already exist, and text is added to it. However, the directory named temp on drive C must exist for the example to complete successfully.

using System;
using System.IO;
using System.Text;

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.
            string createText = "Hello and Welcome" + Environment.NewLine;
            File.WriteAllText(path, createText);
        }

        // This text is always added, making the file longer over time
        // if it is not deleted.
        string appendText = "This is extra text" + Environment.NewLine;
        File.AppendAllText(path, appendText);

        // Open the file to read from.
        string readText = File.ReadAllText(path);
        Console.WriteLine(readText);
    }
}
Imports System
Imports System.IO
Imports System.Text

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 File.Exists(path) = False Then

            ' Create a file to write to.
            Dim createText As String = "Hello and Welcome" + Environment.NewLine
            File.WriteAllText(path, createText)
        End If

        ' This text is always added, making the file longer over time
        ' if it is not deleted.
        Dim appendText As String = "This is extra text" + Environment.NewLine
        File.AppendAllText(path, appendText)

        ' Open the file to read from.
        Dim readText As String = File.ReadAllText(path)
        Console.WriteLine(readText)
    End Sub
End Class

Remarks

Given a string and a file path, this method opens the specified file, appends the string to the end of the file, and then closes the file. The file handle is guaranteed to be closed by this method, even if exceptions are raised.

The method creates the file if it doesn’t exist, but it doesn't create new directories. Therefore, the value of the path parameter must contain existing directories.

Security

FileIOPermission
for access to write to a file or directory. Associated enumeration: Append

AppendAllText(String, String, Encoding) AppendAllText(String, String, Encoding) AppendAllText(String, String, Encoding)

Appends the specified string to the file, creating the file if it does not already exist.

public:
 static void AppendAllText(System::String ^ path, System::String ^ contents, System::Text::Encoding ^ encoding);
public static void AppendAllText (string path, string contents, System.Text.Encoding encoding);
static member AppendAllText : string * string * System.Text.Encoding -> unit
Parameters
path
String String String String

The file to append the specified string to.

contents
String String String String

The string to append to the file.

encoding
Encoding Encoding Encoding Encoding

The character encoding to use.

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).

An I/O error occurred while opening the file.

path specified a file that is read-only.

-or-

This operation is not supported on the current platform.

-or-

path specified a directory.

-or-

The caller does not have the required permission.

The caller does not have the required permission.

Examples

The following code example demonstrates the use of the AppendAllText method to add extra text to the end of a file. In this example, a file is created if it doesn't already exist, and text is added to it. However, the directory named temp on drive C must exist for the example to complete successfully.

using System;
using System.IO;
using System.Text;

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.
            string createText = "Hello and Welcome" + Environment.NewLine;
            File.WriteAllText(path, createText, Encoding.UTF8);
        }

        // This text is always added, making the file longer over time
        // if it is not deleted.
        string appendText = "This is extra text" + Environment.NewLine;
        File.AppendAllText(path, appendText, Encoding.UTF8);

        // Open the file to read from.
        string readText = File.ReadAllText(path);
        Console.WriteLine(readText);
    }
}
Imports System
Imports System.IO
Imports System.Text

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

        ' This text is added only once to the file.
        If File.Exists(path) = False Then

            ' Create a file to write to.
            Dim createText As String = "Hello and Welcome" + Environment.NewLine
            File.WriteAllText(path, createText, Encoding.UTF8)
        End If

        ' This text is always added, making the file longer over time
        ' if it is not deleted.
        Dim appendText As String = "This is extra text" + Environment.NewLine
        File.AppendAllText(path, appendText, Encoding.UTF8)

        ' Open the file to read from.
        Dim readText As String = File.ReadAllText(path)
        Console.WriteLine(readText)
    End Sub
End Class

Remarks

Given a string and a file path, this method opens the specified file, appends the string to the end of the file using the specified encoding, and then closes the file. The file handle is guaranteed to be closed by this method, even if exceptions are raised.

The method creates the file if it doesn’t exist, but it doesn't create new directories. Therefore, the value of the path parameter must contain existing directories.

Security

FileIOPermission
for access to write to a file or directory. Associated enumeration: Append

Applies to