What is the problem of this code and if we correct this is it possible to take any output from this?

Question

int sum (int a, int b=9)
{
return a+b;}
int main()
{int (*psum)(int ,int);
psum=*psum;
std::cout<<(*psum)(9);
}

Answer 1

There's no easy way to achieve that, from what I've read from the following links.

https://stackoverflow.com/questions/9760672/howto-c-function-pointer-with-default-values
https://stackoverflow.com/questions/2576411/function-pointers-with-default-parameters-in-c
https://stackoverflow.com/questions/15615174/function-pointer-and-default-argument

Answer 2

Ipang the problem is why the psum=*psum; is wrong if someone uses refrences in this code would he/she make the true solution?

Answer 3

But what makes you think psum = *psum is corect?

I don't get the relation of references in this matter. What's references got to do with function pointer?

#include <iostream>

int sum( int a )
{
return a * a;
}

int main()
{
// define function pointer <psum> and set it to refer sum() function
int ( *psum )( int ) = sum;

std::cout << psum( 9 ); // invoke sum()
}