[pjmlp]

First of all, if you are comparing K&R against Stroustrup, then you should use C++ARM, not later editions.

Secondly, Bjarne's books include the overview of the standard library, which neither K&R nor its ANSI C revision do.

Third, since everyone keeps using compiler extensions in C, moreso than in C++, those should be included as well.

[unwind]

At least in my ancient copy (second edition, from 1988 I think) K&R most definitely has an overview of the standard library, in Appendix B.

[pjmlp]

I stand corrected on that matter it seems.