C# 0 The Complete Reference

Using a StreamReader

To create a character-based input stream, wrap a byte stream inside a 

StreamReader

.

StreamReader

 defines several constructors. A frequently used one is shown here:

StreamReader(Stream 

stream

)

Here, 

stream

 is the name of an open stream. This constructor throws an 

ArgumentNullException

if

stream

 is null. It throws 

ArgumentException

 if 

stream

 is not opened for input. Once created, 

a

StreamReader

 will automatically handle the conversion of bytes to characters.

The following program creates a simple disk-to-screen utility that reads a text file called 

“test.txt” and displays its contents on the screen. Thus, it is the complement of the key-to-disk 

utility shown in the previous section:

// A simple disk-to-screen utility that demonstrates a StreamReader.

using System;

using System.IO;

class DtoS {

  static void Main() {

    FileStream fin;

    string s;

    try {

      fin = new FileStream("test.txt", FileMode.Open);

    }

    catch(IOException exc) {

      Console.WriteLine("Error Opening File");

      Console.WriteLine(exc.Message);

      return ;

    }

    StreamReader fstr_in = new StreamReader(fin);

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