A function, like a variable, has a memory location in the memory. It is therefore, possible to declare a pointer to the function, which can then be used as argument to another function. The declaration of pointer to a function is as follows:

data _ type (*func) ()

where data – type refers to the data type retuened by the function and func is the name of the function. the formal argument list can also be written.

We can declare a function pointer to point to a specific functions by simple assigning the name of the function to the pointer. For example, the statements

double (*fptr) (), func ();
fptr = func;

declare fptr as a pointer to a function and func as a function and then make fptr to point to function func. To call the function func, we many now use the pointer fptr with the list of parameter.

Program – Illustration of pointer to function

#nclude<stdio.h>
#include<conio.h>
void display ();
void (* fptr) ();
void main ()
{
    clrscr ();
    fptr = display; /*assign address of function*/
    printf (“Address of the display function is %u\n”, fptr);
    (*fptr) (); /*invokes the display () function */
    getch ();
}
void display ()
{
     printf (“inside display function. . .\n”);
}

Output

Address of the display function is 60
Inside display function. . .

In this program, a function named as display () is defined. Another pointer to function named as (*fptr) () is also defined. The statement

fptr = display;

will assign the address of the function display to fptr. Whenever the statement

(*fptr) ()

Is executed, it invokes can be passed to another function as an argument, this allows one function to be transferred another.

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