What about functions pointer list?

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how to use array of function pointers?

I am wondering how one can declare in C a dynamic list of function pointers ? Using a pointer to function pointer ?

Note that http://cdecl.org/ is really useful for these things: searching "array 5 of pointer to function (int, float, double) returning int" gives you an example of a static list. — huon, Aug 02 '12 at 14:53

nhahtdh · Accepted Answer · 2012-08-02T21:22:49.833

2

A pointer to a function pointer, with which you can use to point to a block of dynamically allocated memory. Let's say the function type is void (int):

void (*(*))(int) // Bare type
void (*(*f))(int) // Variable

Or you may want an array to function pointers, in which case:

void (*[10])(int) // Bare type
void (*af[10])(int) // Variable

You can change the parameter and the return type of the functions.

An array of function pointers can be used as a map from number to function to be executed. It is one way to do emulation - for example, after you have obtained the OP code from the instruction, you can execute the operation by using the array of pointer. (This is one way to do so, but I'm not sure whether it is actually done in emulation code).

edited Aug 02 '12 at 21:22

answered Aug 02 '12 at 14:53

nhahtdh

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in your first piece of code void *(*)(int) how to add my list variable name ? – Manuel Selva Aug 02 '12 at 14:56
Edited to answer your question. – nhahtdh Aug 02 '12 at 14:58
Thanks, but how now should I call the function using the pointer to a function pointer ? – Manuel Selva Aug 02 '12 at 20:43
Your first code is a pointer to a function that returns a pointer. Not a pointer to a pointer to a function that returns void. Your second code is a pointer to an array of functions, which is illegal. – newacct Aug 02 '12 at 20:48
@newacct: Fixed. Wanted to bomb the answer, but I fix it anyway since it is accepted. – nhahtdh Aug 02 '12 at 21:25

pb2q · Answer 2 · 2012-08-02T20:55:01.887

1

Yes you can have an array of function pointers.

This might be useful, for instance for collecting a set of callback functions for a specific event.

As an example, consider implementing addEventListener to DOM elements in a browser, where any DOM element can have multiple click events. A simple data structure might be:

void (*clickHandlers[MAX_EVENT_HANDLERS])(EventData arg);

For a dynamic list then allocate a buffer of function pointers using malloc, and realloc as you need more space:

void (**clickHandlers)(EventData arg);

edited Aug 02 '12 at 20:55

answered Aug 02 '12 at 14:53

pb2q

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Yes but my question is how to declare this "buffer of function pointers" – Manuel Selva Aug 02 '12 at 14:58
The second one is wrong. It is a pointer to a function that returns a pointer. – newacct Aug 02 '12 at 20:51

score 1 · Answer 3 · answered Aug 02 '12 at 14:55

1

For a dynamic list, you can use a basic linked list:

struct list {
   int (*func)(int, float, double);
   struct list *next;
}

Or an array of function pointers which is resized as necessary.

answered Aug 02 '12 at 14:55

huon

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What about functions pointer list?

3 Answers3