Question 6.4

Then why are array and pointer declarations interchangeable as function formal parameters?

It's supposed to be a convenience.

Since arrays decay immediately into pointers, an array is never actually passed to a function. Allowing pointer parameters to be declared as arrays is a simply a way of making it look as though the array was being passed--a programmer may wish to emphasize that a parameter is traditionally treated as if it were an array, or that an array (strictly speaking, the address) is traditionally passed. As a convenience, therefore, any parameter declarations which ``look like'' arrays, e.g.

	f(a)
	char a[];
	{ ... }

are treated by the compiler as if they were pointers, since that is what the function will receive if an array is passed:

	f(a)
	char *a;
	{ ... }

This conversion holds only within function formal parameter declarations, nowhere else. If the conversion bothers you, avoid it; many people have concluded that the confusion it causes outweighs the small advantage of having the declaration ``look like'' the call or the uses within the function.