PHP中可以这样写if语句吗?还是我想多了
public function getAreaList($pid = -1) { $map = array(); $pid != -1 && $map['pid'] = $pid; return $this->where($map)->order('`area_id` ASC')->findAll(); }
$pid != -1 && $map['pid'] = $pid;
return $this->where($map)->order('`area_id` ASC')->findAll();
这两句没条件关系吧?上面的一句为什么要用&&连接呢?与直接写
$pid != -1;
$map['pid'] = $pid;
的区别是什么呢?
回复讨论(解决方案)
&& 是逻辑与操作,并是断言的 意思就是 前一个表示式位真,才执行后一个表达式。如果为假,第二个表达式将不会执行
$pid != -1 && $map['pid'] = $pid;
相当于
if($pid != -1) {
$map['pid'] = $pid;
}
这是因为 && 是短路运算,如果 && 前面的表达式不成立的话,后面的表达式就不执行。
其实很不推荐这样写,一来是不清晰,容易让人混淆,二是如果&&后面内容有变化很容易出错。
&& 是逻辑与操作,并是断言的 意思就是 前一个表示式位真,才执行后一个表达式。如果为假,第二个表达式将不会执行 惭愧,惭愧。我一直只是用来做
if(A条件&&B条件){
....
}
A、B都成立是才执行。
$pid != -1 && $map['pid'] = $pid;
相当于
if($pid != -1) {
$map['pid'] = $pid;
}
这是因为 && 是短路运算,如果 && 前面的表达式不成立的话,后面的表达式就不执行。
其实很不推荐这样写,一来是不清晰,容易让人混淆,二是如果&&后面内容有变化很容易出错。 好的谢谢,我自己很少这样写。这是在看看别人的代码,不管怎么说,有收获

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