C++: Reasons for passing objects by value

Question

In Java, all variables containing proper objects are actually references (i.e. pointers). Therefore, method calls with these objects as arguments are always \"by reference\"

Answer 1

If you pass objects to a function by value, that function is free to use those objects as "working" variables without affecting the caller.

Answer 2

It's helpfull to avoid side-effects. If you program need such side-effect use call by reference.