Definition: function prototype

In programming, a declaration of a function to the compiler indicating what types of parameters are passed to it and what value is returned. The compiler can then report an error if a function within the program is not written to conform to the prototype. See function.

The following C example is the simplest prototype. The function displays "Hello World" on screen without receiving any parameters or returning any values to the calling instruction. "Void" means "nothing."

      Prototype

      void printHelloWorld(void);


      Function

      void printHelloWorld(void)
      {
      printf ("Hello World\n");
      }

Prototypes can be a lot more complicated as in this C example where five parameters are passed to a graphics function.

 void  DrawTransparentBitmap(HDC hdc,
          HBITMAP hBitmap,
          int xStart,
          int yStart,
          COLORREF cTransparentColor);