What is the method of encapsulating functions in C language?

The method of encapsulating functions involves defining the functions in a separate source file, declaring the prototypes of the functions and related data structures in a header file. This helps hide the specific implementation details of the functions, only exposing the interface to users, making the code more modular and easier to maintain. Declare the prototypes of the functions as extern in the header file, then define the specific implementations of the functions in the source file. Finally, include the header file in places where these functions need to be used.