顯示文本GET

Question

我犯了一個PHP的形式，並創造了這個錯誤處理腳本：

<?php 
    if(isset($_GET["alert"])) { 
     $alert = $_GET["alert"]; 
     if($_GET["alert"]="nofilled") { 
       echo "<div class='error'>You missed something!</div>"; 
     } 
     elseif($_GET["alert"]="badpass") { 
       echo "<div class='error'>Your passwords don't match!</div>"; 
     } 
     elseif($_GET["alert"]="badusername") { 
       echo "<div class='error'>Your username is too long!</div>"; 
     } 
     elseif($_GET["alert"]="shortpass") { 
       echo "<div class='error'>Your password is too short!</div>"; 
     } 
     elseif($_GET["alert"]="takenusername") { 
       echo "<div class='error'>That username is taken!</div>"; 
     } 
     elseif($_GET["alert"]="takenemail") { 
       echo "<div class='error'>That email already has an account attached to it!</div>"; 
     } 
    } 
?> 

我試圖與「badpass」的GET值運行。出於某種原因，它迴應了'沒有填充'的信息。

我正在學習這一點，我找不到解決方案。你可以快速查看，看看有什麼不對？

Answer 1

您的問題發生是因爲您正在使用'='而不是'=='（1是賦值，2是比較）。 不過，我建議使用下面的方法，因爲它更高效，更清潔：

if(isset($_GET["alert"])) { 
    $alerts = array(
     "nofilled"=>"You missed something!", 
     "badpass"=>"Your passwords don't match!", 
     "badusername"=>"Your username is too long!", 
     "shortpass"=>"Your password is too short!", 
     "takenusername"=>"That username is taken!", 
     "takenemail"=>"That email already has an account attached to it!" 
     ); 

    echo "<div class='error'>". isset($alerts[$_GET['alert']]) ? $alerts[$_GET['alert']] : $alerts[$_GET['nofilled']]. "</div>"; 
} 

• 每@屯的正確意見，我加入的情況下$alerts[$_GET['alert']])不存在爲「nofilled」默認備用。

希望這有助於！

Answer 2

的原因，它默認爲'nofilled'消息，是因爲你使用的=賦值運算符，而不是在==所有conditional statements

=是assignment operator，而==是檢查它的「等於「comparison operator

重寫：

<?php 
    if(isset($_GET["alert"])) { 
     $alert = $_GET["alert"]; 
     if($_GET["alert"]=="nofilled") { 
       echo "<div class='error'>You missed something!</div>"; 
     } 
     elseif($_GET["alert"]=="badpass") { 
       echo "<div class='error'>Your passwords don't match!</div>"; 
     } 
     elseif($_GET["alert"]=="badusername") { 
       echo "<div class='error'>Your username is too long!</div>"; 
     } 
     elseif($_GET["alert"]=="shortpass") { 
       echo "<div class='error'>Your password is too short!</div>"; 
     } 
     elseif($_GET["alert"]=="takenusername") { 
       echo "<div class='error'>That username is taken!</div>"; 
     } 
     elseif($_GET["alert"]=="takenemail") { 
       echo "<div class='error'>That email already has an account attached to it!</div>"; 
     } 
    } 
?> 

請教關於比較操作手冊：

• http://www.php.net/manual/en/language.operators.comparison.php

Answer 3

=使用了分配的東西

==使用了比較

使用==條件中的

if(isset($_GET["alert"])) { 
      $alert = $_GET["alert"]; 
      if($_GET["alert"]=="nofilled") { 
        echo "<div class=='error'>You missed something!</div>"; 
      } 
      elseif($_GET["alert"]=="badpass") { 
        echo "<div class=='error'>Your passwords don't match!</div>"; 
      } 
      elseif($_GET["alert"]=="badusername") { 
        echo "<div class=='error'>Your username is too long!</div>"; 
      } 
      elseif($_GET["alert"]=="shortpass") { 
        echo "<div class=='error'>Your password is too short!</div>"; 
      } 
      elseif($_GET["alert"]=="takenusername") { 
        echo "<div class=='error'>That username is taken!</div>"; 
      } 
      elseif($_GET["alert"]=="takenemail") { 
        echo "<div class=='error'>That email already has an account attached to it!</div>"; 
      } 
     } 

Answer 4

=是一個賦值操作符。因此$_GET["alert"]="nofilled"將"nofilled"指定爲$_GET["alert"]。相反，您應該使用===這是一個身份比較運算符。除非您有很強的理由，否則不應使用==進行比較。 ==會自動進行類型轉換，導致通常很難檢測到的錯誤。由於轉換它也稍微（但當然可以忽略）較慢。

Answer 5

這看起來更像是在使用開關的情況：因爲使用了`

if (isset($_GET["alert"])) { 
    $Errors = array(
    "nofilled" => "You missed something!", 
    "badpass" => "Your passwords don't match!", 
    ... 
    ); 
    echo '<div class = "error">'; 
    if (array_key_exists($_GET['alert'], $Errors)) 
    echo $Errors[$_GET['alert']]; 
    else 
    echo "An undetermined error ocurred"; 
    echo '</div>'; 
    }