Question

So I have been trying and battling with this for a few hours now. I am relatively new to c++ but I read about function pointers and it looked pretty useful. Essentially, what I am attempting to do below is to pass two integer values to the function foo and then multiply it by 10. However, I keep getting the following error: “invalid conversion from ‘int’ to ‘int (*)(int, int)’ [-fpermissive]”.

#include <iostream>

using namespace std;

int foo(int nX, int nY){
    return nX*nY;
}


int multTen(int a, int b, int (*Fn)(int, int)){
    return 10*Fn(a,b);
}

int main(){
    cout << multTen(3,4,foo(3,4)) << endl;
}

Your kind help in this regard is highly appreciated. 🙂

Answer 1

cout << multTen(3,4,foo(3,4)) << endl;
                 // ^^^^^^^ calling function foo and it's return value is passed 
                 // to multTen

The problem is that you are calling the mulTen with the return value of foo as a parameter instead of passing a pointer to it.