C# Read a Text File Line by Line

  1. Read a Text File Line by Line by Using File.ReadLines() Method in C
  2. Read a Text File Line by Line by Using File.ReadAllLines() Method in C
  3. Read a Text File Line by Line by Using StreamReader.ReadLine() Method in C

We can perform several operations on a text file. To use this data in any program, we first need to read that data in a proper data structure.

In C#, there are several ways to read a text file line by line efficiently. Continue reading below to find these ways.

Read a Text File Line by Line by Using File.ReadLines() Method in C

File.ReadLines() method is the best method found to read a text file line by line efficiently. This method returns an Enumerable for large text files, that’s why we have created an Enumerable string object to store the text file.

The correct syntax to use this method is as follows:

File.ReadLines(FileName);

Example Code:

using System;
using System.Collections.Generic;
using System.IO;

public class ReadFile
{
    public static void Main()
    {
      string FileToRead = @"D:\New folder\textfile.txt";
      // Creating enumerable object  
      IEnumerable<string> line = File.ReadLines(FileToRead);
      Console.WriteLine(String.Join(Environment.NewLine, line));   
    }
}

Output:

// All the text, the file contains will display here.

File.ReadLines() method throws an IOException if there is an issue opening the file and FileNotFoundException if the requested file does not exist.

Read a Text File Line by Line by Using File.ReadAllLines() Method in C

File.ReadAllLines() method can also be used to read a file line by line. It does not return an Enumerable but returns a string array that contains all the lines of the text file.

The correct syntax to use this method is as follows:

File.ReadAllLines(FileName);

Example Code:

using System;
using System.IO;

public class ReadFile
{
    public static void Main()
    {
      string FileToRead = @"D:\New folder\textfile.txt";
      // Creating string array  
      string[] lines = File.ReadAllLines(FileToRead);
      Console.WriteLine(String.Join(Environment.NewLine, lines));   
    }
}

Output:

// All the text, the file contains will display here.

This method also throws exceptions just like the File.ReadLines() method. These exceptions are then handled using a try-catch block.

Read a Text File Line by Line by Using StreamReader.ReadLine() Method in C

The StreamReader class in C# provides a method StreamReader.ReadLine(). This method reads a text file to the end line by line.

The correct syntax to use this method is as follows:

//We have to create Streader Object to use this method
StreamReader ObjectName = new StreamReader(FileName);
ObjectName.ReadLine();

Example Code:

using System;
using System.IO;

public class ReadFile
{
    public static void Main()
    {
      string FileToRead = @"D:\New folder\textfile.txt";
      using (StreamReader ReaderObject = new StreamReader(FileToRead))
      {
          string Line;
          // ReaderObject reads a single line, stores it in Line string variable and then displays it on console
          while((Line = ReaderObject.ReadLine()) != null)
          {
              Console.WriteLine(Line);
          }
      }
        
    }
}

Output:

// All the text, the file contains will display here.

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