1、http://en.cppreference.com
What is the purpose of this site?
Our goal is to provide programmers with a complete online reference for the C and C++ languages and standard libraries, i.e. a more convenient version of the C and C++ standards.
The primary objective is to have a good specification of C and C++. That is, things that are implicitly clear to an experienced programmer should be omitted, or at least separated from the main description of a function, constant or class. A good place to demonstrate various use cases is the "example" section of each page. Rationale, implementation notes, domain specific documentation are preferred to be included in the "notes" section of each page.