How to: Read a Text File One Line at a Time (Visual C#)


Updated: July 20, 2015

For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

This example reads the contents of a text file, one line at a time, into a string using the ReadLine method of the StreamReader class. Each text line is stored into the string line and displayed on the screen.

int counter = 0;  
string line;  
// Read the file and display it line by line.  
System.IO.StreamReader file =   
    new System.IO.StreamReader(@"c:\test.txt");  
while((line = file.ReadLine()) != null)  
    System.Console.WriteLine (line);  
System.Console.WriteLine("There were {0} lines.", counter);  
// Suspend the screen.  

Copy the code and paste it into the Main method of a console application.

Replace "c:\test.txt" with the actual file name.

The following conditions may cause an exception:

  • The file may not exist.

Do not make decisions about the contents of the file based on the name of the file. For example, the file myFile.cs may not be a C# source file.

C# Programming Guide
File System and the Registry (C# Programming Guide)