File.WriteAllText(String, String) Method in C# with Examples

Last Updated : 01 Jun, 2020

File.WriteAllText(String, String) is an inbuilt File class method that is used to create a new file, writes the specified string to the file, and then closes the file. If the target file already exists, it is overwritten. Syntax:

public static void WriteAllText (string path, string contents);

Parameter: This function accepts two parameters which are illustrated below:

path: This is the specified file where specified string are going to be written.

contents: This is the specified string to write to the file.

Exceptions:

ArgumentException: The path is a zero-length string, contains only white space, or one or more invalid characters as defined by InvalidPathChars.
ArgumentNullException: The path is null.
PathTooLongException: The specified path, file name, or both exceed the system-defined maximum length.
DirectoryNotFoundException: The specified path is invalid.
IOException: An I/O error occurred while opening the file.
UnauthorizedAccessException: The path specified a file that is read-only. OR the path specified a file that is hidden. OR this operation is not supported on the current platform. OR the path specified a directory. OR the caller does not have the required permission.
NotSupportedException: The path is in an invalid format.
SecurityException: The caller does not have the required permission.

Below are the programs to illustrate the File.WriteAllText(String, String) method. Program 1: Initially, no file was created. Below code itself create a file file.txt and write the specified string array into the file.

CSharp

// C# program to illustrate the usage
// of File.WriteAllText(String, String) method

// Using System, System.IO and
// System.Text namespaces
using System;
using System.IO;
using System.Text;

class GFG {
    public static void Main()
    {
        // Specifying a file
        string path = @"file.txt";

        // Creating a string
        string createText = "GeeksforGeeks" + Environment.NewLine;

        // Writing the string to the file
        File.WriteAllText(path, createText);

        // Reading the contents of the file
        string readText = File.ReadAllText(path);
        Console.WriteLine(readText);
    }
}

Output:

GeeksforGeeks

After running the above code, the above output is shown, and a new file file.txt is created shown below-

Program 2: Initially, a file file.txt is created with some contents shown below-

Below code overwrites the file contents with the specified string.

CSharp

// C# program to illustrate the usage
// of File.WriteAllText(String, String) method

// Using System, System.IO and
// System.Text namespaces
using System;
using System.IO;
using System.Text;

class GFG {
    public static void Main()
    {
        // Specifying a file
        string path = @"file.txt";

        // Creating a string
        string createText = "GFG is a cs portal." + Environment.NewLine;

        // Overwriting the string to the file
        File.WriteAllText(path, createText);

        // Reading the contents of the file
        string readText = File.ReadAllText(path);
        Console.WriteLine(readText);
    }
}