Create a pointer to a function pointer

Question

Is it possible to create a pointer to a function pointer, i.e.

int32_t (*fp[2])(void) = {test_function1, test_function_2}; // initialize a function pointer

<unknown> = fp;

What needs to be written in place of unknown? With "normal" arrays, I could do this:

int a[2] = {0, 1};

int* p = a;

Why do you declare fp as an array of function pointers, if you only want a single pointer? — Some programmer dude
– Some programmer dude, Commented Sep 24, 2014 at 9:34
As for your problem, you need to declare a variable that is a pointer to an array of function pointers, the pointer to an array is the important parts here. And if that's not what you want, then we can't help you unless you tell us what you want? And possibly why you want it (read about the XY problem). — Some programmer dude
– Some programmer dude, Commented Sep 24, 2014 at 9:36
Have you tried just declaring <unknown> as a plain pointer to a function? Remember that arrays decays to pointers to their first element, in your case fp decays to a pointer to test_function1. — Some programmer dude
– Some programmer dude, Commented Sep 24, 2014 at 9:40

Lundin · Accepted Answer · 2015-01-25 18:23:53Z

35

typedef void(*func_ptr_t)(void); // a function pointer

func_ptr_t* ptr_to_func_ptr;     // a pointer to a function pointer - easy to read
func_ptr_t  arr[2];              // an array of function pointers - easy to read

void(**func_ptr_ptr)(void);      // a pointer to a function pointer - hard to read
void(*func_ptr_arr [2])(void);   // an array of function pointers - hard to read

edited Jan 25, 2015 at 18:23

answered Sep 24, 2014 at 9:47

Lundin

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2 Comments

Bionix1441 Over a year ago

if I have void (**foo)(int, int) as a pointer to a function pointer. How can the function pointer be use ?

AlphaGoku Over a year ago

stackoverflow.com/questions/36564473/…

M.M · Accepted Answer · 2014-09-24 09:48:06Z

3

typedef int32_t FP(void);

FP *fp[2] = { test_function1, test_function2 };
FP **p = fp;

edited Sep 24, 2014 at 9:48

answered Sep 24, 2014 at 9:44

M.M

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4 Comments

Some programmer dude Over a year ago

Personally I would probably make the type-alias FP a pointer, but that's just a matter of personal taste. :)

Lundin Over a year ago

@JoachimPileborg I would do that too, function pointers is about the only case where it is ok to hide a pointer behind a typedef. But I think the style in this answer is fine too, since it is consistent with the rule of never typedef:ing away a pointer.

M.M Over a year ago

This way you can also declare functions, e.g. FP test_function1, test_function2;

Lundin Over a year ago

@MattMcNabb That, I would however not recommend, as it will make the reader confuse them with variables. You'd easily make the mistake of declaring a function at local scope, for example.

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