C++ Object Lifetimes - Objects and Lifetimes in C++ Explained
summary
Concrete rules for when an object’s lifetime actually starts and ends, and when the compiler can assume it never happens, are explained with examples: placement new and explicit destructor calls for manual lifetimes, implicit object creation (the “time‑travel” model) for malloc/reuse and memcpy, temporary lifetime extension rules and the loop/for‑range fix in C++20/C++23, provenance aka pointer history that breaks naïve pointer arithmetic, union active‑member and common‑initial‑sequence exceptions, and when to use std::launder, std::bit_cast, or std::start_lifetime_as to avoid UB.
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chapters (10)
- 0:00C++ object lifetimes intro
- 4:16Object storage basics
- 11:38Manual new/delete
- 18:43Temporary objects
- 26:53Placement new
- 31:52Implicit object creation
- 46:10Pointer provenance
- 57:27Type punning
- 1:04:19Invalid pointers
- 1:09:37Best practices
