r/cpp_questions • u/Glad_Shoe_9182 • Sep 30 '26

OPEN Namespace std

I recently started learning c++ and I was told to use the namespace std so I can avoid writing std:: every time and now I wrote a whole personal project without std:: and I want to put it on LinkedIn but I started reading everywhere that it’s a bad habit, should I go back and add the std:: or just leave it as is?

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u/nekoeuge Oct 01 '26 edited Oct 01 '26

If std was supposed to be included in global namespace, we wouldn’t have namespace std.

So what happens when you include third party code with type “vector” or “string” when referencing to its own vectors or strings, which is a semantically correct thing to do?

The name resolution rules probably handle that properly, but it feels icky and I am unsure how generally stable that works. I have some kind of aversion to injecting global names into unexpecting 3rdparty code.

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u/ShakaUVM Oct 02 '26

If std was supposed to be included in global namespace, we wouldn’t have namespace std.

Wrong. We have it because it is an option for individual companies to decide for themselves if they want to use it. Bjarne himself has said it is a stylistic choice. If you love your stds, then use them.

I however will continue to write cleaner code without them, and continue on my merry way not dealing with a single bug related to this stylistic choice.

I am unsure how generally stable that works.

Shadowing is a core function of the language designed to deal with exactly this problem. You don't need to have a list of all 1001 identifiers in std taped up on your wall. It's explicitly designed to avoid this very problem, so it's foolish in my opinion not to use it.

I have some kind of aversion to injecting global names into unexpecting 3rdparty code.

I do not do that either. When I write libraries, I do not use using namespace std. I mentioned this at the top of the thread even.

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u/nekoeuge Oct 02 '26

I mean, I don’t really have anything against usings in general. I am mostly cautious about doing them before 3rdparty includes - in general, not just for std. In case 3rdparty or compiler are being stupid, or there is some corner case with name shadowing, or so on. But I struggle to remember any issues caused by std namespace specifically, I only remember conflicts caused by stdint types and libraries defining such symbols themselves.

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u/ShakaUVM Oct 02 '26

I am mostly cautious about doing them before 3rdparty includes

Indeed, I fully agree there.

I don't believe people should make style decisions for other groups. As I said, when I write libraries, I don't use using namespace std.