When should reference parameters be references to const? What happens if we make a parameter a plain reference when it could be a reference to const

When should reference parameters be references to const? What happens if we make a parameter a plain reference when it could be a reference to const?

// despite appearances, these three declarations of print are equivalent
// each function has a single parameter of type const int*
void print(const int*);
void print(const int[]); // shows the intent that the function takes an
array
void print(const int[10]); // dimension for documentation purposes (at
best)