I suppose you mean that you get a compilation error.
Try to change your code in the main() function to this:
item i("ground beef", 7.55f, 4, 8.75f);
and also the declaration of the constructor
item(char* = " ", float = 0.0f, int = 0, float = 0.0f);
The f after a number is used to say that it is float.
(Spaces are not evil, in the right places they actually help to make the code readable.)