File Class - System.IO

Provides static methods for the creation, copying, deletion, moving, and opening of files, and aids in the creation of FileStream objects.

Namespace: System.IO
Assembly: System.Runtime.Extensions (.NET Core, .NET 5+), mscorlib.dll (.NET Framework)

Syntax

public static class File

The File class is a static class, meaning you do not instantiate it. You call its methods directly using the class name, like File.Exists(...).

Methods

Name	Description
📄 Copy	Copies an existing file to a new location.
🗑 Delete	Deletes a file.
🔍 Exists	Determines whether a file exists.
📝 Move	Moves an existing file to a new location.
📁 ReadAllBytes	Opens a binary file, reads the contents of the file into a byte array, and then closes the file.
📁 ReadAllLines	Opens a text file, reads all lines of the file into a string array, and then closes the file.
📁 ReadAllText	Opens a text file, reads all lines of the file, and then closes the file.
📂 WriteAllBytes	Creates a new file, writes the specified byte array to the file, and then closes the file. If the target file already exists, it is overwritten.
📂 WriteAllLines	Creates a new file, writes a collection of strings to the file, and then closes the file. Each string is written to the file as a separate line.
📂 WriteAllText	Opens a file, writes the specified string to the file, and then closes the file. If the target file already exists, it is overwritten.

Details

Copy

Copies an existing file to a new location.

public static void Copy(string sourceFileName, string destFileName)

public static void Copy(string sourceFileName, string destFileName, bool overwrite)

Parameters:

sourceFileName: The path for the existing file.
destFileName: The path to the new file that is being created.
overwrite: true to allow an existing file to be overwritten; otherwise, false.

Delete

Deletes a file.

public static void Delete(string path)

Parameters:

path: The path of the file to be deleted.

Exists

Determines whether a file exists.

public static bool Exists(string path)

Parameters:

path: The file to check.

Returns: true if the caller has the required permissions and path contains a file; otherwise, false. This method also returns false if any error occurs while accessing the file.

Move

Moves an existing file to a new location.

public static void Move(string sourceFileName, string destFileName)

Parameters:

sourceFileName: The path for the existing file.
destFileName: The path to the new file that is being created.

Note: If destFileName already exists, an exception will be thrown.

ReadAllBytes

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

public static byte[] ReadAllBytes(string path)

Parameters:

path: The file to open for reading.

Returns: A byte array containing the contents of the file.

ReadAllLines

Opens a text file, reads all lines of the file into a string array, and then closes the file.

public static string[] ReadAllLines(string path)

Parameters:

path: The file to read.

Returns: A string array containing all lines of the file.

ReadAllText

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

public static string ReadAllText(string path)

Parameters:

path: The file to read.

Returns: A string containing all the content of the file.

WriteAllBytes

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

public static void WriteAllBytes(string path, byte[] bytes)

Parameters:

path: The file to write to.
bytes: The byte array to write to the file.

WriteAllLines

Creates a new file, writes a collection of strings to the file, and then closes the file. Each string is written to the file as a separate line.

public static void WriteAllLines(string path, IEnumerable contents)

Parameters:

path: The file to write to.
contents: The collection of strings to write to the file.

WriteAllText

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

public static void WriteAllText(string path, string contents)

Parameters:

path: The file to write to.
contents: The string to write to the file.