Help me with the error "Undefined index: referrer in" PHP [duplicate]

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I have the following error:

  

Notice: Undefined index: referrer in   C: \ xampp \ htdocs \ brpg \ register_content.php on line 71

The file register_content.php is: 

<link href="css/login-form.css" type="text/css" rel="stylesheet" />
<div id="reg_top">
    <table align="center">
        <tr>
            <td>
                <h2>Register a new account</h2>
                <p>We are glad you have considered to be a new member and a part of our community and we wish you a wonderful experience here!<br>
                    Please enter the details for your new account below.</p>
                <p><i>Please note that, we do not allow multiple accounts per user and you are hereby creating an MTA game account.</i></p>
            </td>
        </tr>
    </table>
</div>
<div id="reg_mid">

    <form id="register_form" onsubmit="ajax_submit_register();
            return false;" method="post" action="" onkeypress="resetError();">
        <br>
        <table align="center" class="login-form" style="width: 650px;" cellpadding="2">
            <tr>
                <td style="text-align: left;">
                    <b>Username: </b>
                </td>
                <td style="text-align: left;">
                    <input type="text" id="reg_username" placeholder="" maxlength="30" required/>
                </td>
                <td rowspan="5" valign="bottom" style="text-align: left;">
                    <div style="margin-left: 20px;">
                        <b>Prove you're human:</b>
                        <br>

                        <a href="" onclick="ajax_reload_captcha();
                                return false;"><div id="img_captcha"><img src="captcha/captcha.php" /></div></a><br>
                        <input type="text" id="reg_captcha" placeholder="Enter the text above" maxlength="5" required style="width: 146px;" />

                    </div>
                </td>
            </tr>
            <tr>
                <td style="text-align: left;">
                    <b>Password: </b>
                </td>
                <td style="text-align: left;">
                    <input type="password" id="reg_password1" placeholder="" maxlength="50" min="6" required/>
                </td>
            </tr>
            <tr>
                <td style="text-align: left;">
                    <b>Re-type Password: </b>
                </td >
                <td style="text-align: left;">
                    <input type="password" id="reg_password2" placeholder="" maxlength="50" min="6" required/>
                </td>
            </tr>
            <tr>
                <td style="text-align: left;">
                    <b>Email Address: </b>
                </td>
                <td style="text-align: left;">
                    <input type="email" id="reg_email" placeholder="" maxlength="200" min="1" required/>
                </td>
            </tr>
            <tr>
                <td style="text-align: left;">
                    <b>Referrer: </b>
                </td>
                <td style="text-align: left;">

                    <?php 
                                   if($_GET['referrer']){
                                   $referrer = strip_tags($_GET['referrer']);
                                   } else{
                                   $referrer = NULL;
                                   }
                    ?>

                    <input type="text" id="reg_referrer" placeholder="Person who invited you" maxlength="30" value="<?php if ($referrer) echo $referrer; ?>" />
                </td>
            </tr>
            <tr>
                <td colspan="3">
            <center>
                <br>
                <input type="checkbox" id="terms" required/> I have read and agreed to the <a href="http://forums.owlgaming.net/forumdisplay.php?366-Rules" target="_blank">terms and conditions</a>.<br>
                <input type="submit" id="submit_reg" value="Register" style="margin-top: 20px; "/> 
            </center>
            </td>
            </tr>
            <tr>
                <td colspan="3">
                    <div id="error_reg" style="padding-top: 10px; color:red;font-style: italic;font-size: 11px;"></div>
                </td>
            </tr>
            <tr>
                <td align="center" colspan="3">
                    <div id="reg_status"></div>
                </td>
            </tr>
        </table>
    </form>
</div>
<div id="reg_bot">

</div>
<script type="text/javascript" src="js/ajax_register.js"/></script>
    
asked by anonymous 04.01.2017 / 08:28

3 answers

1

You should use isset() , which is the most common and fastest. But you can also use array_key_exists() to check that the array index has been set and is valid.

In this case you could use:

Using isset() : 

$referrer = isset($_GET['referrer']) ? strip_tags($_GET['referrer']) : NULL;

Using array_key_exists() : 

$referrer = array_key_exists('referrer', $_GET) ? strip_tags($_GET['referrer']) : NULL;
    
04.01.2017 / 13:27
2

There is no $ referrer variable and you are trying to check the variable that was not defined at any time.

This is why it is important to check with the isset () function 

if(isset($_GET['referrer'])){
   $referrer = strip_tags($_GET['referrer']);
} else{
  $referrer = NULL;
}
    
04.01.2017 / 12:57
0

It has the detail of checking with isset, but tb has the detail of setting variable as null. If you are going to use a variable within an if, in this context, it is best to set false. 

    <?php 
                   if(isset($_GET['referrer']))
                   {
                       $referrer = strip_tags($_GET['referrer']);
                   } 
                   else
                   {
                       $referrer = false;
                   }
    ?>

    <input type="text" id="reg_referrer" placeholder="Person who invited you" maxlength="30"
value="<?php if ($referrer) echo $referrer; ?>" />
    
04.01.2017 / 13:33
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