How to free memory in try-catch blocks?

Question

I have a simple question hopefully - how does one free memory which was allocated in the try block when the exception occurs? Consider the following code:

try
 {         


        

Answer 1

The easiest way would be to declare the variable before the try block, and then just do the initialization within the block.

Answer 2

Either move the new before the try, so that the pointer is still in scope, or use a smart pointer like shared_ptr or unique_ptr (in a pinch, auto_ptr, but it has issues) that will clean up for you on exit. Exceptions are a huge reason why smart pointers are important.

Answer 3

Yes - if you are considering the simplicity - pointer that is outer to your try block is the solution.

Regards

Answer 4

OK mister Java programmer:

try
{
    // Exception safe dynamic allocation of a block of memory.
    std::vector<char>  heap(50);

    // DO STUFF

    // Note in C++ we use stack based objects and their constructor/destructor
    // TO give a deterministic cleanup, even in the presence of exceptions.
    //
    // Look up RAII (bad name for a fantastic concept).
}
catch (...)
{
    cout << "Error, leaving function now";
    return 1;  // Though why you want to return when you have not fixed the exception is
               // slightly strange. Did you want to rethrow?
}

Answer 5

Agreed with the answers on RAII and smart pointers.

However, if you insist, you can do this:

try { dangerous operations } 
catch { cleanup; throw; }

Answer 6

I have to agree with all those that said RAII, however, I'd use Boost's shared_array instead of an auto_ptr. Auto pointer calls delete and not 'delete []' which will cause leaks with an array.