// const int& n - const = read only reference
#include <iostream>
class Example {
public:
Example() {};
void change(int& n) {
n = 600;
}
void cannotchange(const int& n) {
// n = 871; // error: assignment of read-only reference 'n'
}
};
int main() {
Example obj;
int num;
obj.change(num);
std::cout << num << "\n";
}
/*
run:
600
*/