How many times is this function executed in c++

Question

Here is a piece of c++ code, trying to understand and find out how many times the function is called.

#include <iostream>

int func(int j){
    if (j <= 0) return -1; 
    if (j == 1) return 1;  
    return func(j/2) + func(j-4); 
}

int main(){
    func(4);
}

Answer 1

func(4) will be evaluated as func(2)+func(0) . func(2) will in turn be evaluated as func(1)+func(-2) . In total, you will call func(4) , func(2) , func(1) , func(-2) , func(0) ( 5 times). The resulting expression will be func(1)+func(-2)+func(0) , which is 1+(-1)+(-1) or just -1 .

An easy way to check that would be adding std::cout << “something\n”; in the first line of function definition.