nothrow or exception?

Question

I am a student and I have small knowledge on C++, which I try to expand. This is more of a philosophical question.. I am not trying to implement something.

Since

Answer 1

Running out of memory is expected to be a rare event, so the overhead of throwing an exception when it happens isn't a problem. Implementations can "pre-allocate" any memory that's needed for throwing a std::bad_alloc, to ensure that it's available even when the program has otherwise run out of memory.

The reason for throwing an exception by default, instead of returning null, is that it avoids the need for null checks after every allocation. Many programmers wouldn't bother doing that, and if the program were to continue with a null pointer after a failed allocation, it would probably just crash later with something like a segmentation fault, which doesn't indicate the real cause of the problem. The use of an exception means that if the OOM condition isn't handled, the program will immediately terminate with an error that actually indicates what went wrong, which makes debugging much easier.

It's also easier to write handling code for out-of-memory situations if they throw exceptions: instead of having to individually check the result of every allocation, you can put a catch block somewhere high in the call stack to catch OOM conditions from many places throughout the program.