Why GCC implementation of std::vector operator[] has noexcept specifier

Asked Nov 24 '21 at 12:35

Active Nov 24 '21 at 12:35

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Here - https://en.cppreference.com/w/cpp/container/vector/operator_at it says that operator[] has no noexcept specifier. But If I write:

cout << noexcept(declval<vector<float>>()[declval<size_t>()]) << endl;

I get:

true

Compiled with g++.exe (Rev2, Built by MSYS2 project) 11.2.0. Compilation flags: -std=c++20 -pedantic.

asked Nov 24 '21 at 12:35

Aisec Nory

1

you are basically printing `noexcept(float{});` – 463035818_is_not_an_ai Nov 24 '21 at 12:44
@康桓瑋 It seems yes, Thank you. – Aisec Nory Nov 24 '21 at 12:54
@463035818_is_not_a_number Maybe you right, but here - https://en.cppreference.com/w/cpp/language/noexcept argument to `noexcept` is a function call. Also if I write class `A` with methods: `float& f1();` and `float& f2() noexcept;` and call `noexcept` on them similarly to `vector.operator[]`, I would get `false`, and `true` respectively. – Aisec Nory Nov 24 '21 at 12:58
right, actually I have to admit that I am a little confused as to how `noexcept` works. – 463035818_is_not_an_ai Nov 24 '21 at 13:00

0 Answers0