How output is 66???

Question

#include <iostream>
using namespace std;

int sum(int a, int b=42) {
int result = a + b;
return (result);
}

int main() {
int x = 24;
int y = 36;

//calling the function with both parameters
int result = sum(x, y);
cout << result << endl;
//output 60

//calling the function without b
result = sum(x);
cout << result << endl;
//output 66

return 0;
}

Answer 1

Without specifying second parameter, the default parameter in the function is used for second parameter. Result is 24+42, which is 66.

Answer 2

since you didn't pass any argument value to the second parameter, it's gonna use the default value that you have assigned to the second parameter in function definition