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File.WriteAllLines Method (String, String[])

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

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

public static void WriteAllLines(
	string path,
	string[] contents
)

Parameters

path
Type: System.String

The file to write to.

contents
Type: System.String[]

The string array to write to the file.

ExceptionCondition
ArgumentException

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

ArgumentNullException

Either path or contents is null.

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.

NotSupportedException

path is in an invalid format.

SecurityException

The caller does not have the required permission.

If the target file already exists, it is overwritten.

The default behavior of the WriteAllLines method is to write out data using UTF-8 encoding without a byte order mark (BOM). If it is necessary to include a UTF-8 identifier, such as a byte order mark, at the beginning of a file, use the WriteAllLines(String, String[], Encoding) method overload with UTF8 encoding.

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

The following code example demonstrates the use of the WriteAllLines 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;
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" };
            File.WriteAllLines(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.ReadAllLines(path);
        foreach (string s in readText)
        {
            Console.WriteLine(s);
        }
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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