Lesson 40 +10 XP

Working with Files

C# can read from and write to files using classes in the System.IO namespace.

The File class has methods for creating, reading, writing, and deleting files. To use it, add using System.IO; at the top of your file.

File.WriteAllText("filename.txt", "Hello World!");

This creates filename.txt (or overwrites it) with the given text.

string content = File.ReadAllText("filename.txt");
Console.WriteLine(content);   // Hello World!

File.AppendAllText("filename.txt", " More text!");

if (File.Exists("filename.txt"))
{
  File.Delete("filename.txt");
}

Method	What it does
`File.Exists(path)`	true if the file exists
`File.Copy(src, dst)`	copies a file
`File.Move(src, dst)`	moves a file
`File.ReadAllLines(path)`	reads all lines into a string array
`File.WriteAllLines(path, lines)`	writes a string array as lines

If a file doesn't exist and you try to read it, you'll get an exception. In a later module you'll learn to handle that with try...catch.