File Handling in C#: Reading and Writing Files

File handling is a common task in C# applications. In this guide, you'll learn how to read and write files, work with text and binary files, and handle common file-related operations.

Reading Text Files

Reading a text file is a straightforward process in C#. You can use the `System.IO` namespace to work with files.

Example of reading a text file:

using System;
using System.IO;
class Program
{
    static void Main()
    {
        string filePath = "sample.txt";
        try
        {
            // Read the entire content of the text file
            string content = File.ReadAllText(filePath);
            Console.WriteLine("File Content:\n" + content);
        }
        catch (IOException e)
        {
            Console.WriteLine("An error occurred: " + e.Message);
        }
    }
}
    

Writing Text Files

You can also write to text files using the `File.WriteAllText` method.

Example of writing to a text file:

using System;
using System.IO;
class Program
{
    static void Main()
    {
        string filePath = "output.txt";
        try
        {
            string content = "This is some sample text to write to a file.";
            File.WriteAllText(filePath, content);
            Console.WriteLine("File written successfully.");
        }
        catch (IOException e)
        {
            Console.WriteLine("An error occurred: " + e.Message);
        }
    }
}
    

Reading and Writing Binary Files

To work with binary files, you can use the `BinaryReader` and `BinaryWriter` classes from the `System.IO` namespace.

Example of reading and writing binary files:

using System;
using System.IO;
class Program
{
    static void Main()
    {
        string filePath = "data.dat";
        // Writing binary data to a file
        using (BinaryWriter writer = new BinaryWriter(File.Open(filePath, FileMode.Create)))
        {
            writer.Write(42);
            writer.Write("Hello, Binary World!");
            writer.Write(3.14159265359);
        }
        // Reading binary data from the file
        using (BinaryReader reader = new BinaryReader(File.Open(filePath, FileMode.Open)))
        {
            int integerData = reader.ReadInt32();
            string textData = reader.ReadString();
            double doubleData = reader.ReadDouble();
            Console.WriteLine("Integer: " + integerData);
            Console.WriteLine("Text: " + textData);
            Console.WriteLine("Double: " + doubleData);
        }
    }
}
    

Common File Operations

C# provides various file-related operations, such as checking file existence, deleting files, copying files, and more. These operations are accessible via the `File` and `Directory` classes in the `System.IO` namespace.

Example of checking file existence and deleting a file:

using System;
using System.IO;
class Program
{
    static void Main()
    {
        string filePath = "fileToDelete.txt";
        // Check if a file exists
        if (File.Exists(filePath))
        {
            Console.WriteLine("File exists. Deleting...");
            File.Delete(filePath);
            Console.WriteLine("File deleted.");
        }
        else
        {
            Console.WriteLine("File does not exist.");
        }
    }
}
    

Conclusion

File handling in C# is a crucial aspect of many applications. You've learned how to read and write text and binary files, as well as perform common file-related operations. Proper file handling can help you manage data effectively and interact with the file system in your applications.

Practice working with files in your C# programs to gain confidence in file handling operations. As you continue your programming journey, you'll explore more advanced file-related topics and libraries for handling different types of data and files.