Module 5 - Chapter 1: File Handling in C#

File Handling in C#

Working with the System.IO Namespace

• File: Provides static methods for creating, copying, deleting, moving, and opening files.

• FileInfo: Provides instance methods for creating, copying, deleting, moving, and opening files, and also for retrieving file properties.

• Directory: Provides static methods for creating, moving, and enumerating through directories and subdirectories.

• DirectoryInfo: Provides instance methods for creating, moving, and enumerating through directories and subdirectories.

Reading from a File

Using File.ReadAllText

string content = File.ReadAllText(@"C:\path\to\your\file.txt");
Console.WriteLine(content);

Using File.ReadAllLines

string[] lines = File.ReadAllLines(@"C:\path\to\your\file.txt");
foreach (var line in lines)
{
    Console.WriteLine(line);
}

Using StreamReader

using (StreamReader reader = new StreamReader(@"C:\path\to\your\file.txt"))
{
    string line;
    while ((line = reader.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}

Writing to a File

Using File.WriteAllText

File.WriteAllText(@"C:\path\to\your\file.txt", "Hello, World!");

Using File.WriteAllLines

string[] lines = { "First line", "Second line" };
File.WriteAllLines(@"C:\path\to\your\file.txt", lines);

Using StreamWriter

using (StreamWriter writer = new StreamWriter(@"C:\path\to\your\file.txt"))
{
    writer.WriteLine("Hello, World!");
}

Working with Directories

Creating a Directory

Directory.CreateDirectory(@"C:\path\to\your\directory");

Deleting a Directory

Directory.Delete(@"C:\path\to\your\directory", true); // True to remove directories, subdirectories, and files.

Enumerating Files in a Directory

foreach (string file in Directory.EnumerateFiles(@"C:\path\to\your\directory"))
{
    Console.WriteLine(file);
}

Best Practices for File Handling

• Always use using statements with StreamReader and StreamWriter to ensure that file handles are properly disposed.

• Handle exceptions, such as IOException, to manage errors like file not found, permission issues, or file in use scenarios.

• When dealing with large files, prefer streaming (StreamReader/StreamWriter) over loading the entire file into memory (File.ReadAllText/File.WriteAllText).

Summary