lst-0012-book.cpp
// https://godbolt.org/z/dcKnx3Pno
#include <iostream>
void print_cref(const int& n) { // parameter as constant reference
std::cout << n << " ";
}
int main() {
int x = 5;
print_cref(x); // call with a variable
print_cref(42); // call with a constant literal
}