Answer 1

(1)Library function can be invoked through a header file.On many occasions, the source code is inconvenient or not allowed to be offered,and the header files and binary libraries can be easier supplied to users. Users only need to call library function according to interface implementation. The compiler will extract the corresponding code from library.
(2)Header files can strength type safety check. If an interface is implemented, or be used the way the statement is not consistent in header files, the compiler will point out mistakes. This simple rule can greatly alleviate the burden of debugging and correcting.