Question

I am trying queue implementation in c++. During that I am having this problem.

void Queue::view() 
{
 int i;
 try
 {
  if(Qstatus==EMPTY)
  {
    UnderFlowException ex = UnderFlowException("\nQUEUE IS EMPTY");
    throw ex;
  }
 }

 i=front;
 cout<<"Queue contains...\n";

 while(i <= rear)
 {
  cout<<queue[i]<<" ";
  i++;
 }
}

This gives an error as :

error: expected ‘catch’ before ‘i’

I think this problem is arises since I doesn’t written catch block below try block.
But If want to write the catch block in main(), ( like in this case ), how could I do that?

Before, that Could I do that? If not Why?

Answer 1

catch block must follow the try block. If you want the catch to be in main – that’s where the try has to be too. You can throw everywhere, doesn’t have to be inside a try block within the same function.

It should be something like this:

void Queue::view() 
{
 int i;
 if(Qstatus==EMPTY)
 {
    UnderFlowException ex = UnderFlowException("\nQUEUE IS EMPTY");
    throw ex;
 }

 i=front;
 cout<<"Queue contains...\n";

 while(i <= rear)
  cout<<queue[i]<<" ";
}
/// ...
int main()
{
    Queue q;
    try{
       q.view();
    }
    catch(UnderFlowException ex)
    {
        /// handle
    }
    catch (...)
    {
     /// unexpected exceptions
    }
    // follow the success/handled errors
}