This is a declaration of the function named mageWeapon:
Code:
void mageWeapon(float amount);
it tells the reader what is the function name, parameter types, and return type. You have also used it to indicate the parameter names, which is a good thing as long as it is consistent with the function definition, which looks like this:
Code:
void mageWeapon(float amount)
{
/* ... */
}
the function definition is the declaration of the function that also tells the reader what is the implementation of the function.
This is a function call:
Code:
mageWeapon(amount);
it tells the reader the name of the function that is called as well as the names of the arguments that are passed to the function. In fact, you wrote this in the definition of the mageWeapon function, which makes it a recursive call. In this case, such a recursive call is almost certainly a mistake.
There should be an option to paste as plain text (or to copy as plain text). Xcode is a famous IDE, so it should support such a simple thing.