C++ interview questions and answers

It returns a value or an error without exceptions for expected failures.

Views compose lazily and algorithms take ranges directly.

The size in bytes of an object or type including padding.

Reading or writing past array bounds is UB and can crash or appear to work.

Compile-time branching in templates so discarded branches need not be instantiable.

async may run deferred or on another thread depending on policy.

Store a small interface pointer to a templated model holding the callable.

Some types need alignment beyond new's default.

emplace constructs in place from arguments

Static links code into the binary at build time.

Wrap fopen or OS handles in a class or unique_ptr with a custom deleter.

It reports data races and some lock order issues.

It does not own memory, so temporaries can dangle.

Keep hot fields together, avoid polymorphism in inner loops, and batch processing.

Overload operators only when meaning is obvious like arithmetic types.

Curiously Recurring Template Pattern gives static polymorphism without virtual calls.

Resource Acquisition Is Initialization ties resource lifetime to object lifetime.

A typed null pointer constant safer than 0 or NULL.

It preallocates capacity without changing size.

A simple two-value aggregate used by maps and algorithms.