Demonstrates defining and using a custom exception class
/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
//
// CustExcp.cs -- Demonstrates defining and using a custom exception class
//
// Compile this program with the following command line:
// C:>csc CustExcp.cs
//
namespace nsCustomException
{
using System;
using System.IO;
public class CustExcpclsMain
{
static public void Main (string [] args)
{
if (args.Length < 2)
{
Console.WriteLine ("usage: CustExcp FileName String");
return;
}
try
{
ReadFile (args[0], args[1]);
Console.WriteLine (args[1] + " was not found in " + args[0]);
}
// Custom exception thrown. Display the information.
catch (clsException e)
{
Console.WriteLine ("string {0} first occurs in {1} at Line {2}, Column {3}",
args[1], args[0], e.Line, e.Column);
Console.WriteLine (e.Found);
return;
}
// Check for other possible exceptions.
catch (ArgumentException)
{
Console.WriteLine ("The file name " + args [0] +
" is empty or contains an invalid character");
}
catch (FileNotFoundException)
{
Console.WriteLine ("The file name " + args [0] +
" cannot be found");
}
catch (DirectoryNotFoundException)
{
Console.WriteLine ("The path for " + args [0] +
" is invalid");
}
catch (Exception e)
{
Console.WriteLine (e);
}
}
static public void ReadFile (string FileName, string Find)
{
FileStream strm;
StreamReader reader;
try
{
strm = new FileStream (FileName, FileMode.Open);
reader = new StreamReader (strm);
int Line = 0;
while (reader.Peek () >= 0)
{
++Line;
string str = reader.ReadLine ();
int index = str.IndexOf (Find);
if (index >= 0)
{
reader.Close ();
strm.Close ();
clsException ex = new clsException ();
ex.Line = Line;
ex.Column = index + 1;
ex.Found = str;
throw (ex);
}
}
reader.Close ();
strm.Close ();
return;
}
catch (IOException e)
{
// If file not found, go back and get another name
if (e is FileNotFoundException)
throw (e);
// Code here to handle other IOException classes
Console.WriteLine (e.Message);
throw (new IOException());
}
}
}
// Define a class derived from Exception
class clsException : Exception
{
public int Line = 0;
public int Column = 0;
public string Found = null;
}
}
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