C# StreamReader Code Examples

// File name
string fileName = @"C:\Temp\CSharpAuthors.txt";
StreamReader reader = new StreamReader(fileName);

using System;
using System.IO;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        // File name
        string fileName = @"C:\Temp\CSharpAuthors.txt";

        try
        {
            // Create a StreamReader
            using (StreamReader reader = new StreamReader(fileName))
            {
                string line;
                // Read line by line
                while ((line = reader.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception exp)
        {
            Console.WriteLine(exp.Message);
        }

        Console.ReadKey();
    }
}

FileInfo fi = new FileInfo(fileName);
StreamReader sr = fi.OpenText();
string s = "";

while ((s = sr.ReadLine()) != null)
{
    Console.WriteLine(s);
}

// Create a StreamReader from a FileStream
using (StreamReader reader = new StreamReader(new FileStream(fileName, FileMode.Open)))
{
    string line;
    // Read line by line
    while ((line = reader.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}

The following code snippet creates a StreamReader from a FileStream with Encoding. Encoding supported are ASCII, Unicode, UTF32, UTF7, and UTF8. Encoding is defined in the System.Text namespace.

using (StreamReader reader = new StreamReader(  
new FileStream(fileName, FileMode.Open), Encoding.UTF8))  

The following code snippet creates a StreamReader from a FileStream with encoding and buffer size.

using (StreamReader reader = new StreamReader(  
new FileStream(fileName, FileMode.Open), Encoding.UTF8, true, 1024))  

To learn more about Encoding in C#, visit Encoding/Decoding in C#.

StreamReader.Peak() method

Stream.Reader.Peek() method checks if there are more characters left to read in a file. The method returns an integer. If the value is less than 0, there are no more characters left to read. The following code snippet uses the Peak() method to check if there are more characters left to read in a file.

// Create a StreamReader
using (StreamReader reader = new StreamReader(new FileStream(fileName, FileMode.Open)))
{
    while (reader.Peek() >= 0)
    {
        // Read here
    }
}

StreamReader.ReadBlock() method

StreamReader.Read() method reads a specified maximum number of characters from the current stream and writes the data to a buffer, beginning at the specified index. The position of the underlying stream is advanced by the number of characters that were read into the buffer. The method blocks until either count characters are read or the end of the stream has been reached. This is a blocking version of Read.

StreamReader.ReadBlockAsync() method reads a specified maximum number of characters from the current stream asynchronously and writes the data to a buffer, beginning at the specified index.

StreamReader.Read() method

StreamReader.Read() method reads the next char or next set of chars from the input stream. StreamReader.ReadAsync() method reads the next char or next set of chars from the input stream asynchronously.

The following code snippet reads a stream using the Read() method.

// Create a StreamReader
using (StreamReader reader = new StreamReader(new FileStream(fileName, FileMode.Open)))
{
    while (reader.Peek() >= 0)
    {
        Console.WriteLine((char)reader.Read());
    }
}

StreamReader.ReadLine() method

StreamReader.ReadLine() method reads a line of characters from the current stream and returns the data as a string.

StreamReader.ReadLineAsync() method reads a line of characters from the current stream asynchronously and returns the data as a string.

The following code snippet reads a file using the ReadLine() method.

// Create a StreamReader from a FileStream
using (StreamReader reader = new StreamReader(new FileStream(fileName, FileMode.Open)))
{
    string line;
    // Read line by line
    while ((line = reader.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}

StreamReader.ReadToEnd() method

StreamReader.ReadToEnd() method reads all characters from the current position to the end of the stream.

StreamReader.ReadToEndAsync() method reads all characters from the current position to the end of the stream.

The following code snippet reads the entire file using the ReadToEnd() method.

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

StreamReader Code Example

Here is the complete code example of the use of StreamReader and its methods. The code also reads the content of the file and displays it on the console.

using System;
using System.IO;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        // File name
        string fileName = @"C:\Temp\CSharpAuthors.txt";

        try
        {
            using (StreamReader reader = new StreamReader(fileName))
            {
                Console.WriteLine(reader.ReadToEnd());
            }
        }
        catch (Exception exp)
        {
            Console.WriteLine(exp.Message);
        }

        Console.ReadKey();
    }
}

The output of the above code looks like the following:

Summary

In this article and code sample, we saw how to use a StreamReader class to read a text file.

Next > Working with StreamWriter in C#