Opens a text file, reads all lines of the file, and then closes the file.
(in mscorlib.dll)
Visual Basic (Declaration)
Public Shared Function ReadAllText ( _
path As String _
) As String
Dim path As String
Dim returnValue As String
returnValue = File.ReadAllText(path)
public static string ReadAllText(
string path
)
public:
static String^ ReadAllText(
String^ path
)
public static function ReadAllText(
path : String
) : String
| Exception | Condition |
|---|
| ArgumentException |
path is a zero-length string, contains only white space, or contains one or more invalid characters as defined by InvalidPathChars. |
| ArgumentNullException |
path is nullNothingnullptra null reference (Nothing in Visual Basic). |
| PathTooLongException | The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters. |
| 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. |
This method opens a file, reads each line of the file, and then adds each line as an element of a string. It then closes the file. A line is defined as a sequence of characters followed by a carriage return ('\r'), a line feed ('\n'), or a carriage return immediately followed by a line feed. The resulting string does not contain the terminating carriage return and/or line feed.
This method attempts to automatically detect the encoding of a file based on the presence of byte order marks. Encoding formats UTF-8 and UTF-32 (both big-endian and little-endian) can be detected.
Use the ReadAllText(String, Encoding) method overload when reading files that might contain imported text, because unrecognized characters may not be read correctly.
To use the encoding settings as configured for your operating system, specify the Encoding..::.Default property for the encoding parameter.
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.
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
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);
}
}
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5, 3.0, 2.0
Reference
Other Resources