我们编写了两个验证函数，一个如下所示（一次获取所有字段）：
function check_fields(&$arr,&$msg,$types,$lens,$captions,$requireds) {}
另一个函数如下所示：
function is_valid($field=NULL,$type=0 ,$length=0,$required=true) {}
第一个函数有几行代码，并且大大减少了代码行（大约30-35行甚至更多），另一方面，第二个没有引用的函数增加了代码行（大约30-35行甚至更多） .
我们必须为要验证的每个字段调用第二个函数，但第一个函数 (check_fields) 反之亦然。
我很久以前在一篇文章中读到，从性能角度来看，带有引用参数的函数很糟糕。
现在我们不知道要使用哪个函数。从性能的角度来看，哪个更好？
【问题讨论】：
标签： php function parameter-passing pass-by-reference
当你打电话时，你只记得这个：
<?php
$a = 1 ;
echo "As initial, the real 'a' is..".$a."<br/>";
$b = &$a ; // it's meaning $b has the same value as $a, $b = $a AND SO $a = $b (must be)
$b += 5;
echo "b is equal to: ".$b." and a equal to: ".$a."<br/>";
echo " Now we back as initial, when a=1... (see the source code) <br/>";
$a = 1 ;
echo "After we back : b is equal to: ".$b." and a equal to: ".$a."<br/>";
echo "Wait, why b must follow a? ... <br/> ..what about if we change b alone? (see the source code)<br/>";
$b = 23;
echo "After we change b alone, b equal to: ".$b." and a equal to: ".$a."<br/>";
echo " WHAT ?? a ALSO CHANGED ?? a and b STICK TOGETHER?!! </br>" ;
echo "to 'clear this, we use 'unset' function on a (see the source code)<br/> ";
unset($a);
$b = 66;
$a = 1;
echo "Now, after unset,b is equal to: ".$b." and a equal to: ".$a."<br/>";
?>
输出将是：
As initial, the real 'a' is..1
After the Reference operator...(see the source code)
b is equal to: 11 and a equal to: 11
Now we back as initial... (see the source code)
After we back : b is equal to: 1 and a equal to: 1
Wait, why b must follow a? ...
..what about if we change b alone? (see the source code)
After we change b alone, b equal to: 23 and a equal to: 23
WHAT ?? a ALSO CHANGED ?? a and b STICK TOGETHER?!!
to 'clear this, we use 'unset' function on a (see the source code)
Now, after unset,b is equal to: 66 and a equal to: 1
评论：
为什么$a 发生了变化？那是因为&（与号运算符）将& 作为参考变量，因此它存储在“临时内存”中。当您初始化$b= &$a 时，请参阅我的评论$b = $a 以及 $a = $b，这意味着每当您修改$b 时，$a 也会被修改，反之亦然。 他们被锁住了！这就是引用运算符的简单含义。
也许一开始感觉很迷惑，但是一旦你成为这方面的专家，你就可以像这样处理这个操作符来做一个“切换”功能：
<?php
function bulbswitch(&$switch)
{
$switch = !$switch;
}
function lightbulb($a)
{
if ($a == true) { echo 'a is On <br/>';}
else { echo 'a is Off <br/>';}
}
$a = true ;
echo 'At the begining, a is On, then.... <br/>';
bulbswitch($a);
lightbulb($a);
bulbswitch($a);
lightbulb($a);
bulbswitch($a);
lightbulb($a);
bulbswitch($a);
lightbulb($a);
bulbswitch($a);
lightbulb($a);
bulbswitch($a);
lightbulb($a);
?>
输出将是：
At the begining, a is On, then....
a is Off
a is On
a is Off
a is On
a is Off
a is On
【讨论】：
好吧，我想我在一些网络搜索后自己得到了答案：
【讨论】：
使用更易于使用且更易于维护的解决方案。 您在谈论微优化，这几乎没有用。
【讨论】：