Why c ++ constant pointer or constant reference is passed as function parameters

1. When a large data structure is passed as a parameter, using a reference or pointer as a function parameter can save a copy process and improve efficiency.

View othersCodeThis is often used. Think about why

Void fun1 (const classa &); void fun2 (const classa *);

If classa is a large data structure or class, if you do not use & or * pass a parameter, the real parameter will be assigned to a temporary parameter, which will waste some performance, passing Through pointers or references improves the efficiency.

As for const, I don't want to change its value. Therefore, it is good to use it as much as possible.

2. I did not expect it.