Definition of Function:

What is a function?

• A set of instructions.
• Data pass through FUNCTION and return data to caller.

• To design a program into modules.
• To peform the same instructions.
• To create library of reusable tools.

Function Prototypes                    // This lets the compiler check whether callers have the number of parameters
                                                  //         same as the number of parameters that fumction has. Also,
                                                 // the compiler will check each parameter's data type.  The compiler will see
                                                 // that the data types are matched from calling to called.


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void main()
{
call functions
}


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Definitions of  functions             //The difference between function prototypes and function headers: example:
                                                //   Header:    float Average(float X, float Y, float Z)
                                                //   Prototype:    float Average(float X, float Y, float Z);
                                                //  The only difference is '  ;  ' .