Lecture 7 - Move Semantics and Smart Pointers

This site accompanies ENPM702 - Lecture 7: Move Semantics & Smart Pointers. It organizes the lecture into concise, browsable pages with examples, short exercises, and instructor notes.

Note

Lecture 7 slides (v3.0).

Learning Outcomes

By the end of this session, you will be able to:

  • Explain move semantics and distinguish between lvalues, prvalues, and xvalues in CC.

  • Use rvalue references and std::move to efficiently transfer ownership of resources.

  • Implement and manage smart pointers from <memory> to ensure safe and automatic resource cleanup.

  • Create and use std::unique_ptr with proper initialization, exclusive ownership, and member methods (get(), release(), reset(), swap()).

  • Apply move semantics when passing or returning std::unique_ptr to convey ownership transfer clearly.

  • Use std::shared_ptr to manage shared ownership, explain its control block structure, and utilize methods like use_count() and unique().

  • Pass and return std::shared_ptr correctly using copy semantics and understand reference counting and Return Value Optimization (RVO).

  • Use std::weak_ptr for non-owning observation, employ lock() and expired() safely, and explain how it breaks circular dependencies.

  • Choose the appropriate smart pointer type (unique_ptr, shared_ptr, or weak_ptr) for various ownership and lifetime management scenarios.

Tip

Compile examples with -std=c++17 -Wall -Wextra -pedantic-errors -Werror for strong diagnostics.

Detailed Topics

The following sections explore each topic in Lecture 7:

Lecture 7