“如果"参数评估顺序?

2021-12-12 00:00:00 operator-precedence if-statement c++ 
if(a && b)
{
  do something;
}

是否有可能从右到左评估参数(b -> a)?

is there any possibility to evaluate arguments from right to left(b -> a)?

如果是"，什么影响评估顺序?

if "yes", what influences the evaluation order?

(我使用的是 VS2008)

(i'm using VS2008)

推荐答案

评估顺序由标准规定，为left-to-right.最左边的表达式将始终首先使用 && 子句进行计算.

The evaluation order is specified by the standard and is left-to-right. The left-most expression will always be evaluated first with the && clause.

如果您希望 b 首先被评估:

If you want b to be evaluated first:

if(b && a)
{
  //do something
}

如果两个参数都是方法，并且您希望无论结果如何都对它们进行评估:

If both arguments are methods and you want both of them to be evaluated regardless of their result:

bool rb = b();
bool ra = a();

if ( ra && rb )
{
  //do something
}

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