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Leeds Office (National HQ)

GBdirect Ltd
Leeds Innovation Centre
103 Clarendon Road
West Yorkshire
United Kingdom


tel: +44 (0)870 200 7273
Sales: 0800 651 0338

South East Regional Office

GBdirect Ltd
18 Lynn Rd
United Kingdom


tel: +44 (0)870 200 7273
Sales: 0800 651 0338

Please note: Initial enquiries should always be directed to our UK national office in Leeds (West Yorkshire), even if the enquiry concerns services delivered in London or South/East England. Clients in London and the South East will typically be handled by staff working in the London or Cambridge areas.

5.6. Pointers to functions

A useful technique is the ability to have pointers to functions. Their declaration is easy: write the declaration as it would be for the function, say

int func(int a, float b);

and simply put brackets around the name and a * in front of it: that declares the pointer. Because of precedence, if you don't parenthesize the name, you declare a function returning a pointer:

/* function returning pointer to int */
int *func(int a, float b);

/* pointer to function returning int */
int (*func)(int a, float b);

Once you've got the pointer, you can assign the address of the right sort of function just by using its name: like an array, a function name is turned into an address when it's used in an expression. You can call the function using one of two forms:

/* or */

The second form has been newly blessed by the Standard. Here's a simple example.

#include <stdio.h>
#include <stdlib.h>

void func(int);

      void (*fp)(int);

      fp = func;



func(int arg){
      printf("%d\n", arg);
Example 5.16

If you like writing finite state machines, you might like to know that you can have an array of pointers to functions, with declaration and use like this:

void (*fparr[])(int, float) = {
                              /* initializers */
/* then call one */

fparr[5](1, 3.4);
Example 5.17

But we'll draw a veil over it at this point!