How to use callback function pointer in cpp/C/C++

Program for callback /function pointer in CPP/C/C++

What is function pointers?As we know a pointer is a special variable that folds the address of another variable.
Function pointer is also  a pointer that hold the address of a function.

Int array[10]; // here array is a constant pointer to a 10 element array. That is constant pointer to first element of array.

Can we declare a non-constant pointer to a function? Yes we can .

Int (*funcPtr)();//funcPtr is a pointer to a function that takes no arguments and returns an integers.//parenthesis is must here as we are not assigning the return type.

Int (*funcPtr)(int,int);//funcPtr is a pointer to a function that takes two arguments and returns an integers.

Callback function-callback function is reference to a piece of executable code that is past as arguments to another code.

• This allows a lower level layer code to call a function defined in higher level layer.
• Function pointer are used in many situation like if you are writing a code for sorting an array but instead of hard coding the code of comparison of elements to sort we can provide a way to the user to defined how a particular part of the code will be performed such as array is sorted in ascending or descending order.

Simple example of a function:

#include<stdio.h>
int func(int,int);
int main()
{
int sum;

sum=func(1,2);

printf("\sum=%d\n",sum);

return 0;

}

int func(int a, int b)

{

return a+b;

}

Callback function : example of a function pointer in cpp/C/C++:

//Program for callback function Pointer

#include<stdio.h>

int func(int,int);

int main()

{

//decalring a func ptr taking 2 args and returning a int

int(*funcPtr)(int, int);

int sum;

funcPtr=func;//assiging a function addr to ptr

//calling function through explicit dereference

sum=(*funcPtr)(1,2);

printf("\nSum=%d\n",sum);

//calling function through implicit dereference

sum=funcPtr(1,2);

printf("\nSum=%d\n",sum);

return 0;

}

int func(int a, int b)

{

return a+b;

}

Simples Way to learn Data Structure in C++ CPP or C
C++ Program for Circular Queue implementation using linked list
 
C++ program for Circular Queue implementation using Array

C++ program for reversing single Linked list nodes 

C++ Program for sorted single linked list with class

C++ Program for BST-Binary Search Tree  

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