functions default arguments

Question

#include <iostream>
using namespace std;

int volume(int l=1, int w=1, int h=1) {
return l*w*h;
}

int main() {
cout << volume() << endl;
cout << volume(5) << endl;
cout << volume(2, 3) << endl;
cout << volume(3, 7, 6) << endl;
}

help me understand this code
like when we have volume(5)
then how the formula works???

Answer 1

i think:

volume(5);

is same as:

volume(5, 1, 1);

since in the line the function got declared the parameters have default values given (1).