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

05 Mar, 2021
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. 
C#
// C# program to illustrate the usage// of File.WriteAllLines(String,// String[]) method  // Using System and System.IO,// namespacesusing System;using System.IO;  class GFG {    public static void Main()    {        // Specifying a file        string path = @"file.txt";          // Creating some string array to        // write into the file        string[] createText = { "GFG", "is a", "CS portal." };          // Calling WriteAllLines() function to write        // the specified string array into the file        File.WriteAllLines(path, createText);          // Reading the file contents        string[] readText = File.ReadAllLines(path);        foreach(string s in readText)        {            Console.WriteLine(s);        }    }}
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- 
Program 2: Initially, a file file.txt is created with some contents shown below- 
Below code overwrites the file contents with the specified string array. 
C#
// C# program to illustrate the usage// of File.WriteAllLines(String, // String[]) method  // Using System and System.IO,// namespacesusing System;using System.IO;  class GFG {    public static void Main()    {        // Specifying a file        string path = @"file.txt";          // Creating some string array to        // write into the file        string[] createText = { "GFG", "Geeks", "GeeksforGeeks" };          // Calling WriteAllLines() function to overwrite        // the specified string array into the file        File.WriteAllLines(path, createText);          // Reading the file contents        string[] readText = File.ReadAllLines(path);        foreach(string s in readText)        {            Console.WriteLine(s);        }    }}
Output:  
GFG
Geeks
GeeksforGeeks
After running the above code, the above output is shown, and the file file.txt contents became like shown below: 
 
arorakashish0911
CSharp-File-Handling
C#
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