是零（！0）编译器相关的用C逻辑否定？ [英] Is logical negation of zero (!0) compiler dependent in C?

问题描述

我碰到里面提到的！0的结果是编译器相关的文章。结果可以是1或FF或FFFF等

I came across an article which mentioned that the result of !0 is compiler dependent. The result can be either 1 or FF or FFFF and so on.

至于C99标准6.5.3.3一元算术运算符，

As for C99 standard 6.5.3.3 Unary arithmetic operators,

逻辑否定运算符的结果！是0，如果其操作数的值进行比较
  不等于0，1，如果它的操作数的值进行比较，等于0的结果具有int类型。
  这位前pression！E是等于（0 == E）。

The result of the logical negation operator ! is 0 if the value of its operand compares unequal to 0, 1 if the value of its operand compares equal to 0. The result has type int. The expression !E is equivalent to (0==E).

是不是真的编译器相关的？

Is it really compiler dependent?

推荐答案

您看起来应用于已经回答了你自己的问题，从标准的引用它指定结果必须为0或1。

You seem to have answered you own question already, quoting from the standard where it specifies that the result must be 0 or 1.

因此​​，所有我能猜到是你问所有的C编译器是否符合这方面的标准一致。因为我还没有使用的每一个C编译器写过，我真的不能回答这个问题明确。我从来没有使用过或听说过一个，虽然产生的任何其他的价值 - 并给予这些年来，我在这里度过了挂出，在Usenet等等，它似乎的可能的，如果这样的野兽存在我可能已经听说过它。

As such, about all I can guess is that you're asking whether all C compilers conform with the standard in this respect. Since I haven't used every C compiler ever written, I can't really answer that definitively. I've never used or heard of one that produced any other value though -- and given the years I've spent hanging out here, on Usenet, etc., it seems likely that if such a beast existed I'd probably have heard of it.

编辑：这也许值得一提的是，即使在K＆放大器; R1，它的具体描述生产0或1（§A.7.2）：

It's probably worth noting that even in K&R1, it's specifically described as producing 0 or 1 (§A.7.2):

逻辑否定运算符的结果！是1，如果其操作数的值是0，0，如果它的操作数的值是非零。

The result of the logical negation operator ! is 1 if the value of its operand is 0, 0 if the value of its operand is non-zero.

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