Call by value
Pascal         C/C++
function f(c: char) :
integer;
forward;
TRADITIONAL C:
int f();
ANSI C/C++:
int f(char c);
 OR
int f(char);
NOTE 2: However, it is always good practice to declare a
function before it is used -  and this is mandatory if the return
type is other than int. Further, the C++ compiler (and some
ANSI C compilers issue a warning about “implicit declaration of
function” if you call a previously undeclared function.