ReadAllBytes Method

File.ReadAllBytes Method

Opens a binary file, reads the contents of the file into a byte array, and then closes the file.

Namespace: System.IO
Assembly: mscorlib (in mscorlib.dll)

public static byte[] ReadAllBytes (
	string path
public static byte[] ReadAllBytes (
	String path
public static function ReadAllBytes (
	path : String
) : byte[]
Not applicable.



The file to open for reading.

Return Value

A byte array containing the contents of the file.

Exception typeCondition


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


path is a null reference (Nothing in Visual Basic).


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.


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


An I/O error occurred while opening the file.


path specified a file that is read-only.


This operation is not supported on the current platform.


path specified a directory.


The caller does not have the required permission.


The file specified in path was not found.


path is in an invalid format.


The caller does not have the required permission.

Given a file path, this method opens the file, reads the contents of the file into a byte array, and then closes the file.

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.

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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