用C三元运营商和顺序点 [英] Ternary operator and Sequence Points in C

问题描述

我有以下形式的前pression如下图所示： -

I've an expression of the form shown below :-

while (count)
{
...
...

    index = ((count == 20)? 0 : index++);
...
...
}

现在三元运营商都在C序列点，但我相信，序列点测试部分结束。

Now Ternary operators are sequence points in C but I believe that the sequence point ends at the test part.

这是正确的认识，并因此将这一声明导致不确定的行为？

Is this understanding correct and as such will this statement lead to undefined behaviour ?

推荐答案

右键。还有的条件评估后的序列点，但是下一个序列点是分号终止的声明。所以每当算！= 20 ，你有不确定的行为

Right. There's a sequence point after the evaluation of the condition, but the next sequence point is the semicolon terminating the statement. So whenever count != 20, you have the undefined behaviour

index = index++;

因为首页没有干预序列点修改了两次。

since index is modified twice without intervening sequence point.

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