All the functions in C++ (which are used first and defined later in the program) need to be prototyped.
Function prototypes are usually written at the beginning of the program, ahead of any programmer-defined functions (including
The general form of a function prototype is:
data-type function_name(type 1 arg 1, type 2 arg 2, ..., type n arg n);
data-type represents the data-type of the item that is returned by the function,
function_name represents the function name, and
type 1, type 2, …, type n represents the data-type of the arguments arg 1, arg 2, …, arg n.
Notice that a function prototype resembles the first line of a function definition (though a function prototype ends with a semicolon).
Advantages of Function Prototypes in C++:
Use of function prototypes in C++ offers following advantages:
- Prototypes enables the compilers to provide stronger type checking
- Because of the use of prototypes, the compiler can find and report any questionable type conversions between the arguments used to call a function and the types of its (function;s) parameters
- Because of the use of prototypes, the compiler can also catch differences between the number of arguments used to call a function and the number of parameters in the functions
- Function prototypes help to trap bugs before they occur
- Function prototypes help to verify that the program is working correctly by not allowing functions to be called with mismatched arguments