Explicit qualification of type names in header files

Question

Page 432 of The C++ Programming Language, 4th ed., presents an interface for a desk calculator. It appears names like string and istream are presented "bare" (without qualification to std). Can I emulate this behavior in my own declarations, like this:

header.h

// This is header.h

#include <string>
#include <vector>

extern string s; 
void func(vector<int> vi);

// and so on

...or do names like string and vector need to be explicitly qualified?

It can be done with `using namespace std;`, but see [why it is a bad idea](https://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice) — Yksisarvinen, Oct 12 '19 at 18:33
Please don't. The identifiers in the standard library are way too common to not be qualified. — StoryTeller - Unslander Monica, Oct 12 '19 at 18:33
I suspect that you have skipped over approximately 431 pages of the book. — molbdnilo, Oct 12 '19 at 18:50

score 1 · Accepted Answer · answered Oct 12 '19 at 18:49

Page 89 of the book states

For simplicity, I will rarely use the std:: prefix explicitly in examples. Neither will I always #include the necessary headers explicitly. To compile and run the program fragments here, you must #include the appropriate headers (as listed in §4.4.5, §4.5.5, and §30.2) and make the names they declare accessible.

Explicit qualification of type names in header files

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