If i wont to know the mean or what function do in some library what should i do?

Question

l was used the headers file of each library and it dosnt work with my brain 😅are there any reference or book l can use it

Answer 1

This will show you what you wanna know.
http://www.cplusplus.com/reference/

Answer 2

thanks

Answer 3

just sum up the elements in a for loop and divide it by number of elements