What is pointer to a function?

What is pointer to a function?  

Explanation:

(1) What will be output if you will execute following code?

int * function();

int main(){

auto int *x;

int *(*ptr)();

ptr=&function;

x=(*ptr)();

printf("%d",*x);

}

int *function(){

static int a=10;

return &a;

}

Output: 10

Explanation: Here function is function whose parameter is void data type and return type is pointer to int data type.

x=(*ptr)()

=> x=(*&functyion)() //ptr=&function

=> x=function() //From rule *&p=p

=> x=&a

So, *x = *&a = a =10

(2) What will be output if you will execute following code?

int find(char);

int(*function())(char);

int main(){

int x;

int(*ptr)(char);

ptr=function();

x=(*ptr)('A');

printf("%d",x);

return 0;

}

int find(char c){

return c;

}

int(*function())(char){

return find;

}

Output: 65

Explanation: Here function whose name is function which passing void data type and returning another function whose parameter is char data type and return type is int data type.

x=(*ptr)(‘A’)

=> x= (*function ()) (‘A’) //ptr=function ()

//&find=function () i.e. return type of function ()

=> x= (* &find) (‘A’)

=> x= find (‘A’) //From rule*&p=p

=> x= 65

Blog Author: Vijay Kumar

Go to: Coding Problem Solutions, Java Aptitude