Exception

Question

hi Dudes

Can any one tell me can try block throw the more than one exception at a time... if is possible than how can handle them....?

like below program

using System;

class Test

{

static void Main()

{

try

{

throw new DivideByZeroException();

throw new IndexOutOfRangeException();

}

catch (DivideByZeroException e)

{

Console.WriteLine(e.Message);

}

catch (IndexOutOfRangeException s)

{

Console.WriteLine(s.Message);

}

Console.ReadKey();

}

Zoran Horvat · Answer

You can't throw more than one exception at a time because throwing the exception unwinds current stack frame. Hence after throw new DivideByZeroException() line execution there is no more throw new IndexOutOfRangeException() line. This may be a bit confusing to you unless you understand how call stacks with exceptions work. Imagince classical program without exceptions. Call stack looks like this: function f (called from function g) function g (called from main function) function main Now if we introduce try-catch blocks then they are inserted into call stack. If function g has try-catch from within which it calls function f then call stack looks like this: 1. function f (called from within try-catch from g) 2. catch block handling IndexOutOfRangeException - points to address in g function on which catch block begins 3. function g (called from try-catch from main function) 4. catch block handling DivideByZeroException - points to address in main function on which catch block begins 5. function main Now if f throws DivideByZeroException call stack unwinds - parts 1-3 are popped up and catch block for DivideByZeroException is reached. Then it is examined to find jump addres within main function which actually handles the exception. After that block 4 is also popped up from stack so that call stack looks like this: function main ... and execution continues from the first line of catch block for DivideByZeroException. As a result of this line throw new IndexOutOfRangeException() cannot be reached. Zoran

Vulpes · Answer

It's possible to catch both exceptions by using a nested try/catch block for the first one: using System; class Test { static void Main() { try { try { throw new DivideByZeroException(); } catch (DivideByZeroException e) { Console.WriteLine(e.Message); } throw new IndexOutOfRangeException(); } catch (IndexOutOfRangeException s) { Console.WriteLine(s.Message); } Console.ReadKey(); } } The output is: Attempted to divide by zero. Index was outside the bounds of the array.