Memory Management Class-CAutoVectorPtr

Constructor

CAutoVectorPtr::CAutoVectorPtr is a constructor for the CAutoVectorPtr class template. It is used to create a new CAutoVectorPtr object and take ownership of an existing array.

Here is the syntax for the CAutoVectorPtr constructor:

// type 1
CAutoVectorPtr() throw();
// type 2
explicit CAutoVectorPtr(T* p) throw();
// type 3
CAutoVectorPtr(CAutoVectorPtr<T>& p) throw();

 

Here, ‘p’ is the parameter, which is an existing pointer. The object created will take ownership of the array that is pointed by the ‘p’ parameter. 

Destructor

CAutoVectorPtr::~CAutoVectorPtr is the destructor for the CAutoVectorPtr class template. It is called when a CAutoVectorPtr object goes out of scope. It is responsible for deallocating the object's memory by calling the delete[] operator on the array.

Syntax:

~CAutoVectorPtr() throw();

 

Public Methods

Let us take a look at the public methods provided in this class.

CAutoVectorPtr::Allocate

This method is used to allocate memory for an array of elements of the given type and take ownership of the memory.

Take a look at the syntax:

bool Allocate(size_t nElements);

 

This function takes a single parameter, nElements, which specifies the number of elements in the array. It allocates memory for the array using the new operator and takes ownership of the memory.

It returns true if the memory is allocated successfully and false otherwise.

Here is an example of how you might use the Allocate function to allocate memory for an array of integers:

Code:

CAutoVectorPtr<int> pVector;
pVector.Allocate(10);

// pVector takes ownership of the array and will delete it when it goes out of scope

CAutoVectorPtr::Attach

This method is used to take ownership of an existing pointer. If an object takes ownership of a pointer, the pointer will automatically get deleted when the object goes out of scope. 

Syntax:

void Attach(T* p) throw();

 

Here, the parameter ‘p’ is the pointer. The object created will take its ownership. 

Consider the example below:

Code:

CAutoVectorPtr<int> pInt;
int* pMemoryBlock = new int[10];
pInt.Attach(pMemoryBlock);

 

In this example, the Attach method is used to attach the memory block pointed to by pMemoryBlock to the CAutoVectorPtr object pInt. The CAutoVectorPtr object will take ownership of the memory block and will delete it when the object goes out of scope or is otherwise destroyed.

CAutoVectorPtr::Detach

We call this method to release the ownership of a pointer. It sets the CAutoVectorPtr::m_p member variable to NULL and returns a copy of the pointer. 

Syntax:

T* Detach() throw();

 

Here is an example of how we may use detach:

CAutoVectorPtr<int> pVector(new int[10]);
// ...
int* pArray = pVector.Detach();

CAutoVectorPtr::Free

This method is used to release the memory that the CAutoVectorPtr object is managing and reset the object to its initial state. 

Syntax:

void Free() throw();

 

Consider the following example:

CAutoVectorPtr<int> pVector(new int[10]);
// ...
pVector.Free();

 

After this code is executed, the memory pointed to by pVector is deleted, and pVector is reset to its initial state.

Public Operators

Here are the public operators present in the CAutoVectorPtr class.

CAutoVectorPtr::operator T *

It is the cast operator. It returns a pointer to the object data type defined in the class template. 

Syntax:

operator T*() const throw();

CAutoVectorPtr::operator =

This is the assignment operator which takes a pointer as an argument.

Syntax:

CAutoVectorPtr<T>& operator= (CAutoVectorPtr<T>& p) throw();

 

Here, ‘p’ is the argument. The method returns a reference to the CAutoVectorPtr<T>. The operator= function allows you to assign a new value to the pointer that is being managed by the CAutoVectorPtr object. 

CAutoVectorPtr::m_p

m_p is the pointer data variable member. It holds the pointer information.

Syntax: 

T* m_p;

Frequently Asked Questions

What is the advantage of using CAutoVectorPtr over a regular vector?

One advantage of using CAutoVectorPtr is that it automatically takes care of deleting the vector elements when the object goes out of scope. This can help prevent memory leaks and reduce the risk of invalid pointer dereferences.

Can I use CAutoVectorPtr with primitive types such as int or double?

CAutoVectorPtr is designed to work with pointers to objects, so you cannot use it with primitive types such as int or double directly. However, you can use it with a class or struct that contains a primitive type as a member.

Can I use CAutoVectorPtr with custom classes or structs?

Yes, you can use CAutoVectorPtr with custom classes or structs. However, you need to ensure that the class or struct has a virtual destructor, as CAutoVectorPtr relies on the destructor to delete the objects pointed to by the elements of the vector.

Conclusion

This blog discussed the CAutoVectorPtr class. We understood its definition and learned about its various methods. We saw how we can assign and free memory using this class.

If you wish to learn more about ATL, you can refer to the following blogs.

• CAutoPtr
• CComHeapPtr
• CAutoPtrArray and CAutoPtrList

 

Visit our website to read more such blogs. Make sure you enroll in our other courses as well. You can take mock tests, solve problems, and interview puzzles. Also, you can check out some exciting interview stuff- interview experiences and an interview bundle for placement preparations. Do upvote our blog to help fellow ninjas grow.

Keep Grinding! 🦾

Happy Coding! 💻