Why delete is needed in the definition of the copy-assignment operator?

Question

I am a C++ beginner. And I am doing the exercises in C++ Primer (5th Edition). I found a reference to Exercise 13.8 from Github (Here), which is shown below.

Answer 1

HasPtr::ps is an heap-allocated std::string pointer.

It is allocated and constructed using new in all HasPtr constructors. Therefore, when HasPtr::ps gets replaced by another heap-allocated pointer, the existing memory has to be released using delete to avoid memory leaks.

Note that, in modern C++, you should almost never use new and delete for managing objects like this. Use smart pointers instead, like std::unique_ptr or std::shared_ptr, which take care of memory management for you, safely and conveniently.

I still suggest getting familiar with new and delete, as an huge amount of existing code makes use of them. cppreference.com is a great place to find detailed information about the language.

As Jan Hudec mentioned in the comments, it is generally pretty silly to store an std::string on the heap - std::string is a wrapper around an heap-allocated character array, which already manages the memory for you.