[SOLVED] Is there a way to delete a pointer that has not been assigned with new operator in the destructor? If so, should I delete it in the destructor?

Is there a way to delete a pointer that has not been assigned with new operator in the destructor? If so, should I delete it in the destructor?

For example,

class Test{
private:
   int* foo;
public:
   Test(int* foo){this->foo = foo;}
}

In this case, is there any way I can delete foo in the destructor? Will I have to delete foo in the destructor or at least set it to nullptr?

Solution

Sure, you can. It is legal syntax. And depending on the rest of your program, it might do what you want, or it might be a double delete (delete the same pointer twice) which corrupts the heap and will lead to an eventual crash. (Debugging compilers might catch this.)

One of the reasons the C++ standard template library gave us shared_ptr and unique_ptr is that memory management by hand is hard. It isn't impossible; people did it (or tried to) for many, many years. But it was also a source of many runtime disasters, either the double delete (also called a premature free from the old malloc/free routines), or the opposite, a memory leak. Automatic memory management was one of Java’s selling points as a C/C++-similar language without the memory bug risk. Later C# made the same pitch to users.

I suggest using the STL and thinking about the ownership semantics of your foo. Maybe the Test class should own it; maybe it should share it; maybe it should really have a weak reference. Can't tell from a program fragment. I can only say you should review modern ideas of memory management in C++ and adopt them.