C++ interview questions and answers

Unique_ptr is exclusive ownership, zero overhead, move-only.

To break shared_ptr cycles, like parent-child observers.

A move constructor steals resources from an rvalue so we copy pointers, not buffers.

The compiler generates a function per type I call it with.

Two bases share a grand-base, so a derived object would get two copies of the grand-base.

A per-class table of function pointers for virtual methods.

Realloc or insert can move elements, so old iterators and pointers dangle.

An anonymous function object.

The basic guarantee leaves the program valid

Malloc is C, no constructors, returns void pointer.

Substitution failure is not an error: a bad template candidate is dropped instead of failing the whole program.

Two threads access the same memory, at least one writes, with no happens-before.

A function or variable can be defined only once in the program, with exceptions for inline and templates.

Sequential vector access beats pointer chasing in a list or tree.

If I need a CRUD web app and a GC, C# is faster to ship.

A pointer holds an address and can be reseated or null.

Stack allocates automatic locals and frees them when the scope ends.

Virtual enables dynamic dispatch so a base pointer can call the derived override.

unique_ptr and shared_ptr manage lifetime automatically so I rarely call delete.

vector is contiguous, cache-friendly, and great for random access.