Write string to text file and ensure it always overwrites the existing content.

Use the File.WriteAllText method. It creates the file if it doesn't exist and overwrites it if it exists.

System.IO.File.WriteAllText (@"D:\path.txt", contents);

• If the file exists, this overwrites it.
• If the file does not exist, this creates it.
• Please make sure you have appropriate privileges to write at the location, otherwise you will get an exception.