C++ idiom to avoid memory leaks?

Question

In the following code, there is a memory leak if Info::addPart1() is called multiple times by accident:

typedef struct
{
}part1;

typedef struct
{
}         


        

Answer 1

Checking for nonzero pointer before delete is redundant. delete 0 is guaranteed to be a no-op.

A common way to handle this is

delete _ptr1;
_ptr1 = 0;
_ptr1 = new part1;

Zeroing the pointer ensures there won't be any dangling pointers for example in the case part1 construction throws an exception.