Question

So I decided to dwelve a bit within the pesty C++.

When I call the delete function on a pointer to a simple class that I created I’m greeted by a Debug Assertion Failure -Expression:_BLOCK_TYPE_IS_VALID(pHead->nBlockUse). I assume this is because I’ve handled the string manipulation wrong and thus causing memory corruption.

I created a basic class, [I]animal[/I], that has a string defined that can be set through a function.

// name
char * ptrName;

animal::animal(char * name)
{
 this->SetName(name);
};

animal::~animal()
{
 delete [] ptrName;
}

void animal::SetName(char * name)
{
 ptrName = name;
};

When using the above class as shown below the error occurs. I’ve tried both delete ptrName and delete [] ptrName but to no avail.

animal * cat = new animal("Optimus Prime");
delete cat;

What am I missing?

Answer 1

So I decided to dwelve a bit within the pesty C++.

Then do yourself a favor and use C++ right. That would be to use std::string:

// name
std::string name_;

animal::animal(const std::string& name)
  : name_(name)
{
}

//animal::~animal() // not needed any longer

//note: copying also automatically taken care of by std::string
//animal(const animal&)
//animal& operator=(const animal&)

void animal::SetName(const std::string& name)
{
 name_ = name;
}

Have a look at The Definitive C++ Book Guide and List. I’d recommend Accelerated C++. It comes with a steep learning curve, but since you already know a bit of C++, it’s the 250 pages that might set you on the right track.

As a rule of thumb: Whenever you release a resource (memory or other), and it’s not in the destructor of a class whose solely purpose is to manage this one resource, something is wrong with your design. Personally, I become suspicious whenever I feel the need to write a destructor, copy constructor, or assignment operator.