File Input/Output (I/O)

Introduction to File I/O

File Input/Output (I/O) operations in .NET allow reading from and writing to files on disk. .NET provides several classes in the System.IO namespace to handle file operations.

Reading from a File

To read from a file in .NET, you can use classes like StreamReader or File class methods such as ReadAllText or ReadAllLines.

string path = @"C:\path\to\file.txt";
string content;

using (StreamReader reader = new StreamReader(path)) {
    content = reader.ReadToEnd();
    Console.WriteLine(content);
}
    

Writing to a File

To write to a file in .NET, you can use classes like StreamWriter or File class methods such as WriteAllText or AppendAllText.

string path = @"C:\path\to\file.txt";
string content = "Hello, File I/O in .NET!";

using (StreamWriter writer = new StreamWriter(path, true)) {
    writer.WriteLine(content);
}
    

Working with Binary Files

In addition to text files, .NET supports reading from and writing to binary files using classes like BinaryReader and BinaryWriter.

string binPath = @"C:\path\to\binaryfile.dat";

// Writing to binary file
using (BinaryWriter writer = new BinaryWriter(File.Open(binPath, FileMode.Create))) {
    writer.Write(1.23);
    writer.Write("Hello, binary world!");
}

// Reading from binary file
using (BinaryReader reader = new BinaryReader(File.Open(binPath, FileMode.Open))) {
    double num = reader.ReadDouble();
    string text = reader.ReadString();
    Console.WriteLine(num);
    Console.WriteLine(text);
}
    

Handling File Exceptions

When performing file I/O operations, it's essential to handle exceptions such as file not found, access denied, or I/O errors to ensure robust application behavior.

try {
    string filePath = @"C:\path\to\nonexistentfile.txt";
    string content = File.ReadAllText(filePath);
    Console.WriteLine(content);
}
catch (FileNotFoundException ex) {
    Console.WriteLine("File not found: " + ex.Message);
}
catch (IOException ex) {
    Console.WriteLine("An error occurred: " + ex.Message);
}
    

Conclusion

File Input/Output (I/O) operations are fundamental in .NET for reading from and writing to files. Understanding these concepts and effectively using file handling classes ensures efficient data management in applications.