C# `StreamReader`: Efficiently Reading Character Data from Streams

Learn how to use C#'s `StreamReader` class to read character data from streams, including files. This tutorial demonstrates reading single lines and entire files, using the `Read()` and `ReadLine()` methods, and highlights the importance of using `using` statements for proper resource management and preventing resource leaks.

Using `StreamReader` in C# to Read from Streams

Introduction

The `StreamReader` class in C# is used to read character data from a stream. It's commonly used to read text from files, but it can work with any stream that provides character data. `StreamReader` inherits from `TextReader` and provides convenient methods like `Read()` and `ReadLine()`.

Reading a Single Line with `StreamReader`

This example shows how to open a file and read just one line using `StreamReader`.

using System;
using System.IO;

public class StreamReaderExample {
    public static void Main(string[] args) {
        using (FileStream fileStream = new FileStream("e:\\output.txt", FileMode.OpenOrCreate)) { //Make sure file exists
            using (StreamReader reader = new StreamReader(fileStream)) {
                string line = reader.ReadLine();
                Console.WriteLine(line); //Output the line read
            }
        }
    }
}

Hello C#
        

Reading All Lines with `StreamReader`

This example reads all lines from a file until the end of the file is reached.

using System;
using System.IO;

public class StreamReaderExample {
    public static void Main(string[] args) {
        using (FileStream fileStream = new FileStream("e:\\a.txt", FileMode.OpenOrCreate)) { //Make sure file exists
            using (StreamReader reader = new StreamReader(fileStream)) {
                string line;
                while ((line = reader.ReadLine()) != null) {
                    Console.WriteLine(line);
                }
            }
        }
    }
}

Hello C#
this is file handling
        

Important Note: Resource Management

The examples use a `using` statement. This ensures that the `FileStream` and `StreamReader` are properly closed, even if exceptions occur, preventing resource leaks.

Conclusion

The `StreamReader` class provides a convenient and efficient way to read text from streams in C#. Remember to use proper resource management techniques (like the `using` statement) to prevent resource leaks.