FileInfo - 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.

Try it

public static string FileName = "test.txt";

public static void Main()
{
	SaveFile();
	
	// C# Extension Method: FileInfo - ReadAllBytes
	var bytes = FileName.ToFileInfo().ReadAllBytes();
	
	string newFileName = "newTest.txt";
	
	var file = newFileName.ToFileInfo();
	// C# Extension Method: FileInfo - WriteAllBytes
	file.WriteAllBytes(bytes);
	
	Console.WriteLine(file.ReadAllText());
}

private static void SaveFile()
{
	var html =
    @"<!DOCTYPE html>
<html>
<body>
<h1>This is <b>bold</b> heading</h1>
<p>This is <u>underlined</u> paragraph</p>
<h2>This is <i>italic</i> heading</h2>
</body>
</html> ";
	
	html.SaveAs(FileName);
}

View Source
using System;
using System.IO;

public static partial class Extensions
{
    /// <summary>
    ///     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.
    /// </summary>
    /// <param name="this">The file to write to.</param>
    /// <param name="bytes">The bytes to write to the file.</param>
    /// ###
    /// <exception cref="T:System.ArgumentException">
    ///     <paramref name="this" /> is a zero-length string, contains only
    ///     white space, or contains one or more invalid characters as defined by
    ///     <see
    ///         cref="F:System.IO.Path.InvalidPathChars" />
    ///     .
    /// </exception>
    /// ###
    /// <exception cref="T:System.ArgumentNullException">
    ///     <paramref name="this" /> is null or the byte array is empty.
    /// </exception>
    /// ###
    /// <exception cref="T:System.IO.PathTooLongException">
    ///     The specified @this, 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.
    /// </exception>
    /// ###
    /// <exception cref="T:System.IO.DirectoryNotFoundException">
    ///     The specified @this is invalid (for example, it is on
    ///     an unmapped drive).
    /// </exception>
    /// ###
    /// <exception cref="T:System.IO.IOException">An I/O error occurred while opening the file.</exception>
    /// ###
    /// <exception cref="T:System.UnauthorizedAccessException">
    ///     <paramref name="this" /> specified a file that is
    ///     read-only.-or- This operation is not supported on the current platform.-or-
    ///     <paramref
    ///         name="this" />
    ///     specified a directory.-or- The caller does not have the required permission.
    /// </exception>
    /// ###
    /// <exception cref="T:System.NotSupportedException">
    ///     <paramref name="this" /> is in an invalid format.
    /// </exception>
    /// ###
    /// <exception cref="T:System.Security.SecurityException">The caller does not have the required permission.</exception>
    public static void WriteAllBytes(this FileInfo @this, Byte[] bytes)
    {
        File.WriteAllBytes(@this.FullName, bytes);
    }
}