c - 关于数组下标运算符

Question

引用自 C11 标准:

Array subsripting (§ 6.5.2.1)

The definition of the subscript operator [] is that E1[E2] is identical to (*((E1)+(E2))).

我想知道为什么 E1 周围的括号是必需的(它们在 C89 标准中缺失)，ie 其中表达式可以 (*( E1+(E2))) 与 (*((E1)+(E2))) 不同吗？

Answer 1

根据 http://www.open-std.org/jtc1/sc22/wg14/www/docs/n841.htm , 只是为了清楚起见才插入。这两个表达式在语法上是等价的。

Public Comment Number PC-UK0103
Comment 1.
Category: Editorial change/non-normative contribution
Committee Draft subsection: 6.3.2.1
Title: Array subscripting example
Detailed description:

Paragraph 2 should replace "(*(E1+(E2)))" by "(*((E1)+(E2)))", to avoid confusion. Yes, I know that the syntactic chart makes it quite unambiguous, but the current wording in paragraph 2 is very confusing.