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File.WriteAllLines(String, String[]) Method in C# with Examples

Last Updated : 28 Apr, 2025

File.WriteAllLines(String, String[]) is an inbuilt File class method that is used to create a new file, writes the specified string array to the file, and then closes the file.
Syntax: 
 

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


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

  • path: This is the specified file where specified string array are going to be written.
  • contents: This is the specified string array 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: Either path or contents are 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.WriteAllLines(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.
 

Output: 
 

GFG
is a
CS portal.


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

👁 file.txt


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

👁 file.txt


Below code overwrites the file contents with the specified string array.
 

Output: 
 

GFG
Geeks
GeeksforGeeks


After running the above code, the above output is shown, and the file file.txt contents became like shown below:
 

👁 file.txt


 

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