C# Files


Working With Files

The File class from the System.IO namespace, allows us to work with files:

Example
using System.IO;  // include the System.IO namespace

            File.SomeFileMethod();  // use the file class with methods
            

The file class has many useful ways to create and get information about files. For example:

Method Description
AppendText() Appends text at the end of an existing file
Copy() Copies a file
Create() Creates or overwrites a file
Delete() Deletes a file
Exists() Tests whether the file exists
ReadAllText() Reads the contents of a file
Replace() Replaces the contents of a file with the contents of another file
WriteAllText() Creates a new file and writes the contents to it. If the file already exists, it will be overwritten.

Write To a File and Read It

In the following example, we use the WritAllText() method to create a file called "filename.txt" and write content to it. Then use the ReadAllText() method to read the contents of the file:

Example
using System.IO;  // include the System.IO namespace

            string writeText = "Hello World!";  // Create a text string
            File.WriteAllText("filename.txt", writeText);  // Create a file and write the content of writeText to it
            
            string readText = File.ReadAllText("filename.txt");  // Read the contents of the file
            Console.WriteLine(readText);  // Output the content