用C前pression评估顺序 [英] Order of expression evaluation in C

问题描述

如果我有以下的前pression：

If I have the following expression:

c = (a) * (b)

什么是C90标准说的SUBEX pression'a'和'B'？

What does the C90 standard say about the order evaluation of the subexpression 'a' and 'b'?

推荐答案

有没有特别的顺序，因为乘法运算符是不是一个序列点。序列点包括逗号操作符，一个完整的前pression结束后，和函数调用。因此，评估顺序（A）和（二）要由编译器实现。因此，你不应该试图-做的东西（一），将有要在待观察副作用（二） 为了产生有效的结果。

There is no specified order since the multiplication operator is not a sequence point. Sequence points include the comma operator, the end of a full expression, and function calls. Thus the order of evaluation of (a) and (b) is up to the compiler implementation. Therefore you shouldn't attempt to-do something in (a) that would have a side-effect that you want to be seen in (b) in order to generate a valid result.

例如：

int a=5;
int b = (a++) * (a++); //<== Don't do this!!

如果您想为C序列点，全上市，你可以检查出一个更深入的参考。

If you want a full-listing of sequence points for C, you can check out a more thorough reference here.

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