For example : int fac(int n);
A function prototype in C or C++ is a declaration of a function that omits the function body but does specify the function's name, arity, argument types and return type. While a function definition specifies what a function does, a function prototype can be thought of as specifying its interface.
In a prototype, argument names are optional, however, the type is necessary along with all modifiers
For example : int fac(int n);
Reference 1 # http://en.wikipedia.org/wiki/Signature_(computer_science)
Reference 2 # http://en.wikipedia.org/wiki/Function_prototype
