How To Read A Text File In C#

The File class provides two static methods to read a text file in C#. The File.ReadAllText() method opens a text file, reads all the text in the file into a string, and then closes the file.

 

The following code snippet reads a text file in to a string.

// Read entire text file content in one string
string text = File.ReadAllText(textFile);
Console.WriteLine(text);

The File.ReadAllLines() method opens a text file, reads all lines of the file into a string array, and then closes the file. The following code snippet reads a text file into an array of strings.

// Read a text file line by line.
string[] lines = File.ReadAllLines(textFile);

foreach (string line in lines)
Console.WriteLine(line);

One more way to read a text file is using a StreamReader class that implements a TextReader and reads characters from a byte stream in a particular encoding. The ReadLine method of StreamReader reads one line at a time.

// Read file using StreamReader. Reads file line by line
using(StreamReader file = new StreamReader(textFile)) {
 int counter = 0;
 string ln;

 while ((ln = file.ReadLine()) != null) {
  Console.WriteLine(ln);
  counter++;
 }
 file.Close();
 Console.WriteLine($ "File has {counter} lines.");
}

The complete code sample uses the above-discussed methods to read a text file and display its content to the console. To test this code, find a text file (or create one with some text in it) on your machine and change the "textFile" variable to the full path of your .txt file.

using System;
using System.IO;

namespace ReadATextFile {
 class Program {
  // Default folder
  static readonly string rootFolder = @ "C:\Temp\Data\";
  //Default file. MAKE SURE TO CHANGE THIS LOCATION AND FILE PATH TO YOUR FILE
  static readonly string textFile = @ "C:\Temp\Data\Authors.txt";

  static void Main(string[] args) {
   if (File.Exists(textFile)) {
    // Read entire text file content in one string
    string text = File.ReadAllText(textFile);
    Console.WriteLine(text);
   }

   if (File.Exists(textFile)) {
    // Read a text file line by line.
    string[] lines = File.ReadAllLines(textFile);
    foreach(string line in lines)
    Console.WriteLine(line);
   }

   if (File.Exists(textFile)) {
    // Read file using StreamReader. Reads file line by line
    using(StreamReader file = new StreamReader(textFile)) {
     int counter = 0;
     string ln;

     while ((ln = file.ReadLine()) != null) {
      Console.WriteLine(ln);
      counter++;
     }
     file.Close();
     Console.WriteLine($ "File has {counter} lines.");
    }
   }

   Console.ReadKey();
  }
 }
}