函數中的引用參數（＆$ a），好還是壞？

Question

我們已經譯碼的兩個驗證功能，一個是像下面（它會立刻的所有字段）：

function check_fields(&$arr,&$msg,$types,$lens,$captions,$requireds) {} 

和其他功能是一樣的東西如下：

function is_valid($field=NULL,$type=0 ,$length=0,$required=true) {} 

第一函數幾條代碼行，並大幅減少代碼行（大約30-35行甚至更多），另一方面，第二個沒有引用的函數增加了代碼行（大約30-35行甚至更多）。

我們要呼籲我們要驗證各個領域的第二個功能，但第一個函數（check_fields）是反之亦然。 很久以前我在一篇文章中讀到過，從性能的角度來看，帶參考參數的函數是不好的。

現在我們不知道要使用哪個函數。從性能角度來看哪一個更好？

Answer 1

嗯，我想我有我的答案我自己經過一番網絡搜索：

Do not use PHP references

Answer 2

使用的解決方案，更容易使用，更容易維護。 你正在談論微型優化，這是非常無用的。因爲

---

使用引用您的情況下，它是簡單的解決方案，需要更少的代碼。

Answer 3

你只要記住這一點，當你叫：

<?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/>"; 
    ?> 

和輸出將是：

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 

評論：

爲什麼$a變化？這是因爲&（與號運算符）使得&作爲參考變量，因此它存儲在「臨時存儲器」中。當您初始化$b= &$a時，請參閱我的評論$b = $a和$a = $b，這意味着無論您何時修改$b，$a也被修改，反之亦然。 他們鏈接！這是參考運算符的簡單含義。

也許在開始的時候感覺混亂，但一旦你成爲這方面的專家，您可以處理此操作，使這樣的「開關」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); 
?> 

輸出將是：

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