What does std stand for?

Question

I understand that if there is no using namespace std, and you want to write a cout, you need to have a std::cout.

What does the std represent? Why is std widely used, e.g. std::vector, std::cout, and std::cin?

`std` is an abbreviation of STandarD. It's the namespace that all standard library classes, functions and templates are put in. — Some programmer dude, Jul 12 '22 at 10:59
`std` stands for "standard", and it represents the standard library of C++ — Christian Vincenzo Traina, Jul 12 '22 at 10:59
Voting to reopen. The linked question is a different question. (or not: today I learned there's a reopen hammer) — user253751, Jul 12 '22 at 10:59
Also, [`using namespace std;` is a bad habit](https://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice). — Some programmer dude, Jul 12 '22 at 10:59
it's a namespace, specifically the one reserved for the standard library. You can also define your own namespaces: https://en.cppreference.com/w/cpp/language/namespace — JHBonarius, Jul 12 '22 at 11:00
Cultural reference: https://en.wikipedia.org/wiki/C%2B%2B_Standard_Library - Programmer reference: https://en.cppreference.com/w/ — Christian Vincenzo Traina, Jul 12 '22 at 11:00
Unfortunately not available as duplicate: https://stackoverflow.com/questions/67411397/what-does-using-namespacestd-mean — πάντα ῥεῖ, Jul 12 '22 at 11:01
I gave myself five minutes to come up with a wisecrack about the more widely known, general, alternative acronym for std, but couldn't do it on such a short notice... — Sam Varshavchik, Jul 12 '22 at 11:01
@SamVarshavchik: Steady there Sam. Did you avoid it studiously? — Bathsheba, Jul 12 '22 at 11:02
[DUPE1: What does using namespace::std mean?](https://stackoverflow.com/questions/67411397/what-does-using-namespacestd-mean), [DUPE2: What exactly is a namespace and why is it necessary](https://stackoverflow.com/questions/32161199/what-exactly-is-a-namespace-and-why-is-it-necessary), [DUPE3: Why std::cout instead of simply cout?](https://stackoverflow.com/questions/10950083/why-stdcout-instead-of-simply-cout) — Jason, Jul 12 '22 at 11:02
@scissors127 Refer to a [good c++ book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list). This is explained in literally every beginner level c++ book. — Jason, Jul 12 '22 at 11:06
As per [std](https://www.acronymfinder.com/STD.html) stands for **standard**, or **sexually transmitted disease**, or **short term disability**, or **Star Trek: Discovery**, or a few other things. In the context of C++, I think it's the second one. — Eljay, Jul 12 '22 at 11:08
I thought that `std` is the namespace of STL, the C++ Standard Type Library. — Dominique, Jul 12 '22 at 11:38
@Dominique Nope. The STL was a library that was designed in the 90s, and its design influenced the C++ standard library (the library described in ratified ANSI or ISO C++ standards). The STL and the C++ standard library have some features in common, but they are not the same thing. Most of the C++ standard library (there are some things where this is not true) is placed, by the C++ standard, into a namespace called `std`. `std` is just a shorthand for "standard". — Peter, Jul 12 '22 at 11:51
@Eljay I've never, AFAIK, caught a sexually transmitted disease as a result of doing software development in C++. In fact, I think that knowing something about C++ contributes to a lower susceptibility ;-) — Peter, Jul 12 '22 at 11:55

score 5 · Answer 1 · answered Jul 12 '22 at 11:07

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std stands for "standard".

The reason why so much standard stuff goes in the std namespace is simple: Before namespaces, different code written by different people would often use the same name and cause a conflict. For example, my drink dispenser program from 1994 might have a class ofstream which is an orange fanta stream. When a new version of C++ came along and added ofstream which was an output file stream, my program wouldn't compile any more, or it'd crash.

Okay, orange-fanta-stream is silly, but major operating systems do have C functions called open, close, and index. I'm sure many people have tried to make global variables called open, and then their programs have crashed.

In C++, all the new C++ standard stuff is inside std::, so as long I don't call something in my program std, they can add new stuff inside std:: and it definitely won't cause this problem. Unfortunately all the stuff that C++ inherits from C is outside std::, so you still can't make a global variable called open (on Linux), but at least it's a start.

answered Jul 12 '22 at 11:07

user253751

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Could've closed this by adding more accurate dupes instead of reopening it. This is a very common SO question. There are plenty of question for this. – Jason Jul 12 '22 at 11:08
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@AnoopRana I thought so too, but when I looked, I found that most of them are asking what a namespace is, or how to use a namespace, not *why* a namespace is. – user253751 Jul 12 '22 at 11:08
See [here](https://stackoverflow.com/a/67411572/12002570) it is already explained: *"`std` is an abbreviation of "standard". `std` is the "standard namespace". `cout`, `cin` and a lot of other functions are defined within it"* – Jason Jul 12 '22 at 11:10
@AnoopRana this answer says "std stands for standard" but it doesn't say why std is widely used - the rest of the answer is how to use a namespace. – user253751 Jul 12 '22 at 11:11
The fundamental reason for using a namespace is the same. It doesn't matter what abbreviation you use for the namespace itself. If one understands what are namespace and why we should/shouldn't use them then one automatically understands why `std` is used as well. Ofcourse there may also be historical reasons for using `std` and not some other abbreviation. – Jason Jul 12 '22 at 11:12
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@AnoopRana the answer you linked does not explain the reason for using a namespace. Nor do any of the others I looked at. It only explains the abbreviation, as well as how to use it. – user253751 Jul 12 '22 at 11:25

What does std stand for?

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