File.WriteAllBytes() Method in C# with Examples - GeeksforGeeks

26 Feb, 2021
File.WriteAllBytes(String) is an inbuilt File class method that is used to create a new file then writes the specified byte array to the file and then closes the file. If the target file already exists, it is overwritten. 
Syntax:  
public static void WriteAllBytes (string path, byte[] bytes);
Parameter: This function accepts two parameters which are illustrated below:  
path: This is the specified file where the byte array is going to be written.
bytes: This is the specified bytes that are going to be written into 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 or the byte array is empty.
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.WriteAllBytes(String, Byte[]) method.Program 1: Initially, no file was created. Below code, itself creates a file file.txt and writes some specified byte array and then finally close the file. 
CSharp
// C# program to illustrate the usage// of File.WriteAllBytes() method // Using System, System.IO// and System.Text namespacesusing System;using System.IO;using System.Text; class GFG {    static void Main(string[] args)    {        // Specifying a file name        var path = @"file.txt";         // Specifying a byte array        string text = "GFG is a CS portal.";        byte[] data = Encoding.ASCII.GetBytes(text);         // Calling the WriteAllBytes() function        // to write specified byte array to the file        File.WriteAllBytes(path, data);        Console.WriteLine("The data has been written to the file.");    }}
Output:  
The data has been written to the file.
Above code gives the output as shown above and creates a file with some specified contents shown below- 
Program 2: Initially, a file was created with some contents shown below: 
Below code, overwrites the above file contents with a specified byte array data. 
CSharp
// C# program to illustrate the usage// of File.WriteAllBytes() method // Using System, System.IO// and System.Text namespacesusing System;using System.IO;using System.Text; class GFG {    static void Main(string[] args)    {        // Specifying a file name        var path = @"file.txt";         // Specifying a byte array data        string text = "GeeksforGeeks";        byte[] data = Encoding.ASCII.GetBytes(text);         // Calling the WriteAllBytes() function        // to overwrite the file contents with the        // specified byte array data        File.WriteAllBytes(path, data);        Console.WriteLine("The data has been overwritten to the file.");    }}
Output:  
The data has been overwritten to the file.
After running above code, the above output is shown and the file contents get overwritten which is shown below- 
 
arorakashish0911
CSharp-File-Handling
C#
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