C# 4 and .NET 4

356 ❘ ChaPTer 15 errOrs And exceptiOns
The program then continues to ask for more numbers for processing until the user simply presses the Enter
key without entering anything.
You should note that this code does not provide a good example of when to use
exception handling. As already indicated, the idea of exceptions is that they are
provided for exceptional circumstances. Users are always typing in silly things, so this
situation doesn’t really count. Normally, your program will handle incorrect user input
by performing an instant check and asking the user to retype the input if there is a
problem. However, generating exceptional situations is diffi cult in a small example that
you can read through in a few minutes! So, we will tolerate this bad practice for now
to demonstrate how exceptions work. The examples that follow present more realistic
situations.
The code for SimpleExceptions looks like this:
using System;
namespace Wrox.ProCSharp.AdvancedCSharp
{
public class MainEntryPoint
{
public static void Main()
{
while (true)
{
try
{
string userInput;
Console.Write("Input a number between 0 and 5 " +
"(or just hit return to exit) > ");
userInput = Console.ReadLine();
if (userInput == "")
{
break;
}
int index = Convert.ToInt32(userInput);
if (index < 0 || index > 5)
{
throw new IndexOutOfRangeException(
"You typed in " + userInput);
}
Console.WriteLine("Your number was " + index);
}
catch (IndexOutOfRangeException ex)
{
Console.WriteLine("Exception: " +
"Number should be between 0 and 5. {0}", ex.Message);
}
catch (Exception ex)
{
Console.WriteLine(
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