### Question 4.12

I've seen different methods used for calling functions via pointers. What's the story?

Originally, a pointer to a function had to be ``turned into'' a ``real'' function, with the `*` operator (and an extra pair of parentheses, to keep the precedence straight), before calling:

    	int r, func(), (*fp)() = func;
    	r = (*fp)();

It can also be argued that functions are always called via pointers, and that ``real'' function names always decay implicitly into pointers (in expressions, as they do in initializations; see question 1.34). This reasoning, made widespread through `pcc` and adopted in the ANSI standard, means that

    	r = fp();

is legal and works correctly, whether `fp` is the name of a function or a pointer to one. (The usage has always been unambiguous; there is nothing you ever could have done with a function pointer followed by an argument list except call the function pointed to.) An explicit `*` is still allowed (and recommended, if portability to older compilers is important).

See also question 1.34.

References: K&R1 Sec. 5.12 p. 116
K&R2 Sec. 5.11 p. 120
ANSI Sec. 3.3.2.2
ISO Sec. 6.3.2.2
Rationale Sec. 3.3.2.2
H&S Sec. 5.8 p. 147, Sec. 7.4.3 p. 190

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