Thread: What happens to pointer on myFunction(new myClass()); ?

Did a search on this and didn't come up with anything, and it's starting to baffle me. I was working on some class functions that require a pointer to another class. I was originally implementing as below, but then changed it to the second chunk of code. When I changed it to the second I noticed my values were now gone, and my objects no longer existed.

So when you use a function in this manner, myFunction(new myClass()); does the pointer to the newly created myClass get deleted after the function returns?

Code:

// this is the way i implemented it, and stored values,
// using assign(new someOtherClass()); works fine in this case
// and 'data' retains the information, but what happens to
// the pointer to the newly made someOtherClass? Memory leak???

class myClass
{
private:
    someOtherClass data;

public:
    
    // ignore that there are no constructors
    
    void assign(someOtherClass* otherClass)
    {
        data = (*otherClass);
    }
};

Code:

// this is the second way I implemented it, thinking it was better,
// but 'data' ends up not retaining the pointer after the
// assign(new someOtherClass()) function is called, what gives???

class myClass
{
private:
    someOtherClass* data;

public:
    
    // ignore that there are no constructors
    
    void assign(someOtherClass* otherClass)
    {
        if (data != NULL) delete data;
        data = otherClass;
    }
};

Originally Posted by scwizzo

So when you use a function in this manner, myFunction(new myClass()); does the pointer to the newly created myClass get deleted after the function returns?

No, it does not get deleted.

Your first version does result in a memory leak. Your second version should be closer to being correct, so I suggest that you post the smallest and simplest compilable program that demonstrates the problem. The question to ask is: does your myClass object have ownership of the someOtherClass object that its member variable named data points to?

Originally Posted by laserlight

so I suggest that you post the smallest and simplest compilable program that demonstrates the problem

*Slams head on desk* When I went back to find the code for copy-pasting, I ended up noticing I was deleting the argument passed to the function (before it was used), instead of the class' member variable that I was originally wanting. Sometimes I surprise myself...

Originally Posted by whiteflags

Hmm, well did you delete otherClass before you checked data?

Yes that sums up what I was doing.

Ever thought of using smart pointers?