File.WriteAllText Method

Reference

Definition

Namespace:: System.IO

Assemblies:: netstandard.dll, System.Runtime.dll

Assemblies:: mscorlib.dll, System.IO.FileSystem.dll

Assemblies:: netstandard.dll, System.IO.FileSystem.dll

Assemblies:: netstandard.dll, System.IO.FileSystem.dll, System.Runtime.dll

Assembly:: System.IO.FileSystem.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Creates a new file, write the contents to the file, and then closes the file. If the target file already exists, it is truncated and overwritten.

Overloads

WriteAllText(String, ReadOnlySpan<Char>)	Creates a new file, writes the specified string to the file, and then closes the file. If the target file already exists, it is truncated and overwritten.
WriteAllText(String, String)	Creates a new file, writes the specified string to the file, and then closes the file. If the target file already exists, it is truncated and overwritten.
WriteAllText(String, ReadOnlySpan<Char>, Encoding)	Creates a new file, writes the specified string to the file using the specified encoding, and then closes the file. If the target file already exists, it is truncated and overwritten.
WriteAllText(String, String, Encoding)	Creates a new file, writes the specified string to the file using the specified encoding, and then closes the file. If the target file already exists, it is truncated and overwritten.

WriteAllText(String, ReadOnlySpan<Char>)

Creates a new file, writes the specified string to the file, and then closes the file.

If the target file already exists, it is truncated and overwritten.

public:
 static void WriteAllText(System::String ^ path, ReadOnlySpan<char> contents);

public static void WriteAllText(string path, ReadOnlySpan<char> contents);

static member WriteAllText : string * ReadOnlySpan<char> -> unit

Public Shared Sub WriteAllText (path As String, contents As ReadOnlySpan(Of Char))

Parameters

path: String

The file to write to.

contents: ReadOnlySpan<Char>

The characters to write to the file.

Exceptions

ArgumentNullException

path is null.

ArgumentException

path is empty.

PathTooLongException

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

DirectoryNotFoundException

The specified path is invalid (for example, it is on an unmapped drive).

IOException

An I/O error occurred while opening the file.

UnauthorizedAccessException

path specified a file that is read-only.

-or-

path specified a file that is hidden.

-or-

path specified a directory.

-or-

This operation is not supported on the current platform.

The caller does not have the required permission.

NotSupportedException

path is in an invalid format.

Remarks

This method uses UTF-8 encoding without a Byte-Order Mark (BOM), so using the GetPreamble() method will return an empty byte array. If it is necessary to include a UTF-8 identifier, such as a byte order mark, at the beginning of a file, use the WriteAllText(String, ReadOnlySpan<Char>, Encoding) method.

Applies to

.NET 10 and .NET 9

Product	Versions
.NET	9, 10

WriteAllText(String, String)

Source:: File.cs

Source:: File.cs

Source:: File.cs

Creates a new file, writes the specified string to the file, and then closes the file. If the target file already exists, it is truncated and overwritten.

public:
 static void WriteAllText(System::String ^ path, System::String ^ contents);

public static void WriteAllText(string path, string contents);

public static void WriteAllText(string path, string? contents);

static member WriteAllText : string * string -> unit

Public Shared Sub WriteAllText (path As String, contents As String)

Parameters

path: String

The file to write to.

contents: String

The string to write to the file.

Exceptions

ArgumentException

.NET Framework and .NET Core versions older than 2.1: path is a zero-length string, contains only white space, or contains one or more invalid characters. You can query for invalid characters by using the GetInvalidPathChars() method.

ArgumentNullException

path is null.

PathTooLongException

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

DirectoryNotFoundException

The specified path is invalid (for example, it is on an unmapped drive).

IOException

An I/O error occurred while opening the file.

UnauthorizedAccessException

path specified a file that is read-only.

-or-

path specified a file that is hidden.

-or-

This operation is not supported on the current platform.

-or-

path specified a directory.

-or-

The caller does not have the required permission.

NotSupportedException

path is in an invalid format.

SecurityException

The caller does not have the required permission.

Examples

The following code example demonstrates the use of the WriteAllText method to write text to a file. In this example a file is created, if it doesn't already exist, and text is added to it.

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);
    }
}

open System
open System.IO

let path = @"c:\temp\MyTest.txt"

// This text is added only once to the file.
if File.Exists path |> not then
    // Create a file to write to.
    let 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.
let appendText =
    "This is extra text" + Environment.NewLine

File.AppendAllText(path, appendText)

// Open the file to read from.
let readText = File.ReadAllText path
printfn $"{readText}"

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

This method uses UTF-8 encoding without a Byte-Order Mark (BOM), so using the GetPreamble method will return an empty byte array. If it is necessary to include a UTF-8 identifier, such as a byte order mark, at the beginning of a file, use the WriteAllText(String, String, Encoding) method overload with UTF8 encoding.

Given a string and a file path, this method opens the specified file, writes the string to the file, and then closes the file.

Applies to

.NET 10 and other versions

Product	Versions
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.3, 1.4, 1.6, 2.0, 2.1
UWP	10.0

WriteAllText(String, ReadOnlySpan<Char>, Encoding)

Creates a new file, writes the specified string to the file using the specified encoding, and then closes the file.

If the target file already exists, it is truncated and overwritten.

public:
 static void WriteAllText(System::String ^ path, ReadOnlySpan<char> contents, System::Text::Encoding ^ encoding);

public static void WriteAllText(string path, ReadOnlySpan<char> contents, System.Text.Encoding encoding);

static member WriteAllText : string * ReadOnlySpan<char> * System.Text.Encoding -> unit

Public Shared Sub WriteAllText (path As String, contents As ReadOnlySpan(Of Char), encoding As Encoding)

Parameters

path: String

The file to write to.

contents: ReadOnlySpan<Char>

The characters to write to the file.

encoding: Encoding

The encoding to apply to the string.

Exceptions

ArgumentNullException

path or encoding is null.

ArgumentException

path is empty.

PathTooLongException

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

DirectoryNotFoundException

The specified path is invalid (for example, it is on an unmapped drive).

IOException

An I/O error occurred while opening the file.

UnauthorizedAccessException

path specified a file that is read-only.

-or-

path specified a file that is hidden.

-or-

path specified a directory.

-or-

The caller does not have the required permission.

-or-

This operation is not supported on the current platform.

NotSupportedException

path is in an invalid format.

Applies to

.NET 10 and .NET 9

Product	Versions
.NET	9, 10

WriteAllText(String, String, Encoding)

Source:: File.cs

Source:: File.cs

Source:: File.cs

Creates a new file, writes the specified string to the file using the specified encoding, and then closes the file. If the target file already exists, it is truncated and overwritten.

public:
 static void WriteAllText(System::String ^ path, System::String ^ contents, System::Text::Encoding ^ encoding);

public static void WriteAllText(string path, string contents, System.Text.Encoding encoding);

public static void WriteAllText(string path, string? contents, System.Text.Encoding encoding);

static member WriteAllText : string * string * System.Text.Encoding -> unit

Public Shared Sub WriteAllText (path As String, contents As String, encoding As Encoding)

Parameters

path: String

The file to write to.

contents: String

The string to write to the file.

encoding: Encoding

The encoding to apply to the string.

Exceptions

ArgumentException

ArgumentNullException

path is null.

PathTooLongException

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

DirectoryNotFoundException

The specified path is invalid (for example, it is on an unmapped drive).

IOException

An I/O error occurred while opening the file.

UnauthorizedAccessException

path specified a file that is read-only.

-or-

path specified a file that is hidden.

-or-

This operation is not supported on the current platform.

-or-

path specified a directory.

-or-

The caller does not have the required permission.

NotSupportedException

path is in an invalid format.

SecurityException

The caller does not have the required permission.

Examples

The following code example demonstrates the use of the WriteAllText method to write text to a file. In this example a file is created, if it doesn't already exist, and text is added to it.

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);
    }
}

open System
open System.IO
open System.Text

let path = @"c:\temp\MyTest.txt"

// This text is added only once to the file.
if File.Exists path |> not then
    // Create a file to write to.
    let 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.
let appendText =
    "This is extra text" + Environment.NewLine

File.AppendAllText(path, appendText, Encoding.UTF8)

// Open the file to read from.
let readText = File.ReadAllText path
printfn $"{readText}"

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, writes the string to 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.

Applies to

.NET 10 and other versions

Product	Versions
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.3, 1.4, 1.6, 2.0, 2.1
UWP	10.0

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File.WriteAllText Method

Definition

Overloads

WriteAllText(String, ReadOnlySpan<Char>)

Parameters

Exceptions

Remarks

Applies to

WriteAllText(String, String)

Parameters

Exceptions

Examples

Remarks

Applies to

WriteAllText(String, ReadOnlySpan<Char>, Encoding)

Parameters

Exceptions

Applies to

WriteAllText(String, String, Encoding)

Parameters

Exceptions

Examples

Remarks

Applies to

Additional resources