$matches = [1,2,3];
$k = array_search(0,$matches);
if(isset($k)){
unset($matches[$k]);
}
var_dump($matches);
返回array(2) {
[1]=>
int(2)
[2]=>
int(3)
}
isset-----null 或未定义的变量才为false,isset(false)返回true
另外unset($matches[false])会去掉k为0的数组
isset判断用是否!==false
