C# 0 The Complete Reference

PART I

C h a p t e r   1 4 :  

U s i n g   I / O  

379

PART IPART I

    Console.WriteLine("Enter text ('stop' to quit).");

    do {

      Console.Write(": ");

      str = Console.ReadLine();

      if(str != "stop") {

        str = str + "\r\n"; // add newline

        try {

          fstr_out.Write(str);

          } catch(IOException exc) {

             Console.WriteLine("Error Writing File");

             Console.WriteLine(exc.Message);

             break;

          }

      }

    } while(str != "stop");

    fstr_out.Close();

  }

}

In some cases, it might be more convenient to open a file directly using 

StreamWriter

.

To do so, use one of these constructors:

StreamWriter(string 

fi lename

)

StreamWriter(string 

fi lename

, bool 

appendFlag

)

Here, 

filename

 specifies the name of the file to open, which can include a full path specifier. 

In the second form, if 

appendFlag

 is true, then output is appended to the end of an existing 

file. Otherwise, output overwrites the specified file. In both cases, if the file does not exist, 

it is created. Also, both throw an 

IOException

 if an I/O error occurs. Other exceptions are 

also possible.

Here is the key-to-disk program rewritten so that it uses 

StreamWriter

 to open the 

output file:

// Open a file using StreamWriter.

using System;

using System.IO;

class KtoD {

  static void Main() {

    string str;

    StreamWriter fstr_out;

    try {

      fstr_out = new StreamWriter("test.txt");

    }

    catch(IOException exc) {

      Console.WriteLine("Cannot Open File");

      Console.WriteLine(exc.Message);

      return ;

    }

    Console.WriteLine("Enter text ('stop' to quit).");

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380

 

P a r t   I :  

T h e   C #   L a n g u a g e

    do {

      Console.Write(": ");

      str = Console.ReadLine();

      if(str != "stop") {

        str = str + "\r\n"; // add newline

        try {

          fstr_out.Write(str);

        } catch(IOException exc) {

          Console.WriteLine("Error Writing File");

          Console.WriteLine(exc.Message);

          break;

        }

      }

    } while(str != "stop");

    fstr_out.Close();

  }

}