Is copy elision guaranteed?

i.e. copy elision of temporary objects in return statements generally being guaranteed irrespective of c++ 17.

Is return value optimization guaranteed?

It de-facto mandates what was known as Return Value Optimization (RVO) and allows non-copyable, non-movable objects to be returned in such a way. Compilers often perform Named Return Value Optimization (NRVO) in such cases, but it is not guaranteed.

Under what conditions copy elision is performed?

Copy elision is an optimization implemented by most compilers to prevent extra (potentially expensive) copies in certain situations. It makes returning by value or pass-by-value feasible in practice (restrictions apply).

How does return value optimization work?

RVO is a compiler technique to avoid copying objects when the object is returned as function value. This optimization helps a function to efficiently return large objects while also simplifying the function’s interface and eliminating scope for errors.

Does C++ return by value?

C++ functions can return by value, by reference (but don’t return a local variable by reference), or by pointer (again, don’t return a local by pointer). When returning by value, the compiler can often do optimizations that make it equally as fast as returning by reference, without the problem of dangling references.

Does C have RVO?

> Note also that C doesn’t have return-value-optimization, hence all your struct-returning functions will cause a call to memcpy (won’t happen when compiled in C++ mode of course). What? RVO is precisely needed because a copy in C++ can run arbitrary code and so is not as easy to ellide as a memcpy.

Does C have return value optimization?

> Note also that C doesn’t have return-value-optimization, hence all your struct-returning functions will cause a call to memcpy (won’t happen when compiled in C++ mode of course).

What is return optimization?

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Should I return reference or value?

Most of the time, return by value will be sufficient for your needs. It’s also the most flexible and safest way to return information to the caller. However, return by reference or address can also be useful, particularly when working with dynamically allocated classes or structs.

What is return object optimization?

In the context of the C++ programming language, return value optimization (RVO) is a compiler optimization that involves eliminating the temporary object created to hold a function’s return value. RVO is allowed to change the observable behaviour of the resulting program by the C++ standard.