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C# Files

Working With Files

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


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

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

The File class has many useful methods for creating and getting 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.

For a full list of File methods, go to Microsoft .Net File Class 参考.

Write To a File and Read It

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


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

The output will be:

Hello World!
Run example »

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