File.ReadAllText Method (System.IO) (2023)

  • Reference

Definition

Namespace:
System.IO
Assemblies:
mscorlib.dll, System.IO.FileSystem.dll
Assembly:
System.IO.FileSystem.dll
Assembly:
System.Runtime.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.

Opens a text file, reads all the text in the file into a string, and then closes the file.

Overloads

ReadAllText(String)

Opens a text file, reads all the text in the file, and then closes the file.

ReadAllText(String, Encoding)

Opens a file, reads all text in the file with the specified encoding, and then closes the file.

ReadAllText(String)

Opens a text file, reads all the text in the file, and then closes the file.

public: static System::String ^ ReadAllText(System::String ^ path);
public static string ReadAllText (string path);
static member ReadAllText : string -> string
Public Shared Function ReadAllText (path As String) As String

Parameters

path
String

The file to open for reading.

Returns

String

A string containing all the text in 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.

IOException

An I/O error occurred while opening the file.

UnauthorizedAccessException

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.

FileNotFoundException

The file specified in path was not found.

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 ReadAllText method to display the contents of 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 Systemopen System.IOlet 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.NewLineFile.AppendAllText(path, appendText)// Open the file to read from.let readText = File.ReadAllText pathprintfn $"{readText}"
Imports System.IOImports System.TextPublic 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 SubEnd Class

Remarks

This method opens a file, reads all the text in the file, and returns it as a string. It then closes the file.

This method attempts to automatically detect the encoding of a file based on the presence of byte order marks. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 text if the file starts with the appropriate byte order marks.

Use the ReadAllText(String, Encoding) method overload when reading files that might contain imported text, because unrecognized characters may not be read correctly.

The file handle is guaranteed to be closed by this method, even if exceptions are raised.

See also

  • File and Stream I/O
  • Reading Text From A File
  • How to: Write Text to a File
  • How to: Read and Write to a Newly Created Data File

Applies to

ReadAllText(String, Encoding)

Opens a file, reads all text in the file with the specified encoding, and then closes the file.

public: static System::String ^ ReadAllText(System::String ^ path, System::Text::Encoding ^ encoding);
public static string ReadAllText (string path, System.Text.Encoding encoding);
static member ReadAllText : string * System.Text.Encoding -> string
Public Shared Function ReadAllText (path As String, encoding As Encoding) As String

Parameters

path
String

The file to open for reading.

encoding
Encoding

The encoding applied to the contents of the file.

Returns

String

A string containing all text in 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-

This operation is not supported on the current platform.

-or-

path specified a directory.

-or-

The caller does not have the required permission.

FileNotFoundException

The file specified in path was not found.

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 ReadAllText method to display the contents of 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 Systemopen System.IOopen System.Textlet 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.NewLineFile.AppendAllText(path, appendText, Encoding.UTF8)// Open the file to read from.let readText = File.ReadAllText pathprintfn $"{readText}"
Imports System.IOImports System.TextPublic 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 SubEnd Class

Remarks

This method opens a file, reads all the text in the file, and returns it as a string. It then closes the file.

This method attempts to automatically detect the encoding of a file based on the presence of byte order marks. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 text if the file starts with the appropriate byte order marks.

The file handle is guaranteed to be closed by this method, even if exceptions are raised.

To use the encoding settings as configured for your operating system, specify the Encoding.Default property for the encoding parameter.

See also

  • File and Stream I/O
  • Reading Text From A File
  • How to: Write Text to a File
  • How to: Read and Write to a Newly Created Data File

Applies to

Top Articles
Latest Posts
Article information

Author: Delena Feil

Last Updated: 12/26/2022

Views: 6223

Rating: 4.4 / 5 (45 voted)

Reviews: 92% of readers found this page helpful

Author information

Name: Delena Feil

Birthday: 1998-08-29

Address: 747 Lubowitz Run, Sidmouth, HI 90646-5543

Phone: +99513241752844

Job: Design Supervisor

Hobby: Digital arts, Lacemaking, Air sports, Running, Scouting, Shooting, Puzzles

Introduction: My name is Delena Feil, I am a clean, splendid, calm, fancy, jolly, bright, faithful person who loves writing and wants to share my knowledge and understanding with you.