PHP运算符优先级错误？ [英] PHP operator precedence bug?

问题描述

结果：

var_dump(null != $a = 15);
var_dump($a);

是：

bool(true)
int(15)

不触发错误？
由于！= （不等于运算符）的优先级高于 = code> $ a 应该与 null 比较？

Why is this script not triggering an error? Since != (not equal operator) has a higher precedence than = (assignment operator), $a should be compared to null first?

推荐答案

我能找到的唯一原因是文档说这仍然是合法的： http://php.net/manual/en/language.operators.precedence.php#example-129

The only reason I can find is that the documentation says that this is still legal: http://php.net/manual/en/language.operators.precedence.php#example-129

这似乎是上面表格中显示的例外。

It seems to be an exception to what is shown in the table above.

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