Difference between new and delete operator in c++

In C++, new and delete are operators used to dynamically allocate and deallocate memory, respectively.

new operator:

The new operator is used to dynamically allocate memory for an object or an array. When you use new, the following happens:

  1. The memory is allocated from the free store (also known as the heap).
  2. The memory is initialized with the default constructor of the object (if it has one).
  3. A pointer to the allocated memory is returned.

Example:

int* p = new int;

This code allocates memory for an int object and returns a pointer to it.

delete operator:

The delete operator is used to deallocate memory that was previously allocated using new. When you use delete, the following happens:

  1. The memory is deallocated from the free store.
  2. The object's destructor is called (if it has one).

Example:

delete p;

This code deallocates the memory that was allocated using new and calls the destructor of the int object.

Key differences:

  1. Allocation vs. Deallocation: new allocates memory, while delete deallocates memory.
  2. Initialization: new initializes the memory with the default constructor of the object, while delete does not perform any initialization.
  3. Destruction: delete calls the destructor of the object, while new does not.
  4. Return value: new returns a pointer to the allocated memory, while delete does not return any value.

Best practices:

  1. Always use new and delete together to ensure that memory is properly allocated and deallocated.
  2. Use smart pointers (e.g., unique_ptr, shared_ptr) instead of raw pointers and new/delete to manage memory.
  3. Avoid using new and delete in performance-critical code, as they can introduce overhead and potential bugs.

In summary, new is used to allocate memory and initialize objects, while delete is used to deallocate memory and destroy objects.