const reference in function arguments

• Few good reasons to use const reference in function arguments:

  • Avoids copying overhead, saving space and time

  • Preserves caller's peace of mind

  • Makes altering object (through reference) a compiler error.

  • Should always be the first choice when passing non-mutable objects:

    
        void print_point( Point const& pt )
    
    

  • Pointer should probably be the first choice when passing mutable objects. Some people argue that programs should never use non-const references for readability reasons.