https://stackoverflow.com/questions/3473675/are-negative-array-indexes-allowed-in-c

A postfix expression followed by an expression in square brackets [] is a subscripted
designation of an element of an array object. The definition of the subscript operator []
is that E1[E2] is identical to (*((E1)+(E2))). Because of the conversion rules that
apply to the binary + operator, if E1 is an array object (equivalently, a pointer to the
initial element of an array object) and E2 is an integer, E1[E2] designates the E2-th
element of E1 (counting from zero).

这里说明了下标是个整数，你说没用不代表其他人也必要用到，我在处理图像的时候就经常这么干。

【 在 here080 的大作中提到: 】
: 没有意义。编译能行不代表符合标准。就算符合标准也不要用这种可能有歧义也没必要的功能。
:
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FROM 114.255.101.*