C++的基础语法里提供了||&&两个逻辑操作符还有,(comma)运算符。在类中我们也可以重载这些操作符，但是不要这样做，我会在这篇文章中写出标准描述以及不能重载的原因。

logical AND operator:The && operator groups left-to-right. The operands are both contextually converted to bool (Clause 4). The result is true if both operands are true and false otherwise. Unlike &, && guarantees left-to-right evaluation: the second operand is not evaluated if the first operand is false.
The result is a bool. If the second expression is evaluated, every value computation and side effect associated with the first expression is sequenced before every value computation and side effect associated with the second expression.

logical OR operator:The || operator groups left-to-right. The operands are both contextually converted to bool (Clause 4). It returns true if either of its operands is true, and false otherwise. Unlike |, || guarantees left-to-right evaluation; moreover, the second operand is not evaluated if the first operand evaluates to true.
The result is a bool. If the second expression is evaluated, every value computation and side effect associated with the first expression is sequenced before every value computation and side effect associated with the second expression.

• AND：If the second expression is evaluated, every value computation and side effect associated with the first expression is sequenced before every value computation and side effect associated with the second expression.
• OR：If the second expression is evaluated, every value computation and side effect associated with the first expression is sequenced before every value computation and side effect associated with the second expression.

[ISO/IEC 14882:2014]All side effects of argument evaluations are sequenced before the function is entered.

[ISO/IEC 14882:2014 §8.3.6.9]The order of evaluation of function arguments is unspecified.

1. 先自增aobj
2. 自增b
3. 然后调用A::operator||

[ISO/IEC 14882:2014]A pair of expressions separated by a comma is evaluated left-to-right; the left expression is a discarded-value expression.

1. 实参在进入函数体之前就已经求值完毕
2. 重载operator,的求值顺序是不一定的