After a function is declared and defined, it can be called from
anywhere within the program: from within the
from another function, and even from itself. Calling the function
involves specifying the function name, followed by the function call
operator and any data values the function expects to receive. These
values are the arguments for the parameters defined for the
function. This process is called passing arguments to the function.
- Pass by value, which copies the value of an argument to the corresponding parameter in the called function;
- Pass by pointer, which passes a pointer argument to the corresponding parameter in the called function;
- Pass by reference (C++ only), which passes the reference of an argument to the corresponding parameter in the called function.
If a class has a destructor or a copy constructor that does more than a bitwise copy, passing a class object by value results in the construction of a temporary object that is actually passed by reference.
- The class needs a copy constructor.
- The class does not have a user-defined copy constructor.
- A copy constructor cannot be generated for that class.
A function call is always an rvalue.
- An lvalue if the result type is an lvalue reference type or an rvalue reference to a function type
- An xvalue if the result type is an rvalue reference to an object type
- A (prvalue) rvalue in other cases