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.

Answer 2

On the far extreme of possible ways to deal with memory leaks is the boehm garbage collector, a conservative mark & sweep collector. Interestingly, this can be used in addition to all the good advice offered in other answers.

Answer 3

You should take a look at RAII

Answer 4

Use a smart pointer such as boost:shared_ptr , boost:scoped_ptr is recommended to manage the raw pointer. auto_ptr is tricky to work with, you need pay attention to that.

Answer 5

Option 1: Use Java :)

Option 2: Use auto_ptr

std::auto_ptr<part1> _ptr1;
std::auto_ptr<part2> _ptr2;

public:
addPart1()
{
   _ptr1 = auto_ptr<part1>(new part1);
}

...

// no destructor is needed