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Question

我犯了一个PHP的形式，并创造了这个错误处理脚本：

<?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>"; 
     } 
    } 
?> 

我试图与“badpass”的GET值运行。出于某种原因，它回应了'没有填充'的信息。

我正在学习这一点，我找不到解决方案。你可以快速查看，看看有什么不对？

Answer 1

您的问题发生是因为您正在使用'='而不是'=='（1是赋值，2是比较）。 不过，我建议使用下面的方法，因为它更高效，更清洁：

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@屯的正确意见，我加入的情况下$alerts[$_GET['alert']])不存在为“nofilled”默认备用。

希望这有助于！

Answer 2

的原因，它默认为'nofilled'消息，是因为你使用的=赋值运算符，而不是在==所有conditional statements

=是assignment operator，而==是检查它的“等于“comparison operator

重写：

<?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>"; 
     } 
    } 
?> 

请教关于比较操作手册：

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

Answer 3

=使用了分配的东西

==使用了比较

使用==条件中的

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

=是一个赋值操作符。因此$_GET["alert"]="nofilled"将"nofilled"指定为$_GET["alert"]。相反，您应该使用===这是一个身份比较运算符。除非您有很强的理由，否则不应使用==进行比较。 ==会自动进行类型转换，导致通常很难检测到的错误。由于转换它也稍微（但当然可以忽略）较慢。

Answer 5

这看起来更像是在使用开关的情况：因为使用了`

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>'; 
    }