How to assign a pointer to function using C program?

Pointer to function

It holds the base address of function definition in memory.

Declaration

datatype (*pointername) ();

The name of the function itself specifies the base address of the function. So, initialization is done using function name.

For example,

int (*p) ();
p = display; //display () is a function that is defined.

Example 1

We shall see a program for calling a function using pointer to function −

#include<stdio.h>
main (){
   int (*p) (); //declaring pointer to function
   clrscr ();
   p = display;
   *(p) (); //calling pointer to function
   getch ();
}
display (){ //called function present at pointer location
   printf(“Hello”);
}

Output

Hello

Example 2

Let us consider another program explaining the concept of pointer to function −

#include <stdio.h>
void show(int* p){
   (*p)++; // add 1 to *p
}
int main(){
   int* ptr, a = 20;
   ptr = &a;
   show(ptr);
   printf("%d", *ptr); // 21
   return 0;
}

Output

21