Explicit Deletion in C++ Despite Program Exit

When working with dynamic memory allocation in C++, developers often wonder if it's necessary to manually call the "delete" operator on heap-allocated variables before program exit. This article delves into this topic.

In the C++ main function, a pointer to a dynamically allocated variable (heap memory) is used. As the application exits, is this memory automatically released? Generally, it is. However, even in these cases, it's considered good practice to always explicitly delete heap allocations, as it ensures proper resource management and adherence to C++ memory management principles.

Consider the following example:

int main(...) {
    A* a = new A();
    a->DoSomething();
    delete a;
    return 0;
}

In this example, the "delete a" statement explicitly deallocates the heap memory allocated for the "a" pointer. Explicit deletion ensures that the destructor for the "A" object is invoked, which is important for executing any cleanup tasks defined within the destructor, such as closing open files or releasing other resources.

Moreover, if the code is refactored and moved to a different location within the application, the explicit "delete" statement remains necessary to prevent potential memory leaks. The OS may eventually release the memory when the program exits, but it's better to have explicit control over memory management.

Additionally, the "delete" operator ensures that the memory occupied by the object is returned to the free store, preventing memory fragmentation and performance issues in future allocations.

Therefore, it's recommended to always explicitly delete heap allocations in C++, even if it appears that they will be automatically deallocated upon program exit. This ensures proper memory management, destructor execution, and adherence to C++ memory management best practices.