c++ - cpp 运算符重载操作数位置 [] vs ==

Question

char& operator[] 与 bool operator== 有何不同？一个将操作数放在 [] 之间，而另一个将操作数放在 == 之后。它怎么知道把操作数放在哪里？左括号和右括号有什么特别的技巧吗？

Answer 1

How does it know where to put the operand?

嗯。因为标准是这么说的？

§11.5.5 Subscripting [over.sub]/1 :

operator[] shall be a non-static member function with exactly one parameter. It implements the subscripting syntax

postfix-expression [ expr-or-braced-init-list ]

Thus, a subscripting expression x[y] is interpreted as x.operator[](y) for a class object x of type T if T​::​operator[](T1) exists and if the operator is selected as the best match function by the overload resolution mechanism ([over.match.best]).