PHP复选框，带2个正确答案

Question

I'm doing a quiz the below is a html checkbox.

<p>3. The J2EE components includes:</p>
            <p><label for="JavaDevelopmentKit">
               <input type="checkbox" id="JavaDevelopmentKit" name="category[]" value="JavaDevelopmentKit"/>Java Development Kit</label></p>
            <p><label for="VisualStudio">
               <input type="checkbox" id="VisualStudio" name="category[]" value="VisualStudio"/>Uses Visual Studio</label></p>
            <p><label for="WriteOnce">
               <input type="checkbox" id="WriteOnce" name="category[]" value="WriteOnce"/>Write Once Run Anywhere technology</label></p>

this is my php code

 if ($q3 == ""){
            $errMsg = "<p>You must answer question 3.</p>";
        }
        else if (isset($_POST['JavaDevelopmentKit']) && isset($_POST['WriteOnce'])
                $total++;
            }

My PHP for checkbox is not working.

Even if I change it to

 if ($q3 == ""){
                    $errMsg = "<p>You must answer question 3.</p>";
                }
                else if (isset($_POST['JavaDevelopmentKit'])
                        $total++;
                    }

Total is not increment by 1.

[edit]

I did how @mahaidery told me to, and my current php is

if ($q3 == ""){
    $errMsg = "<p>You must answer question 3.</p>";
}
else if (isset($_POST['category'])){
    $i = 0;
    foreach($_POST['category'] as $k=>$v){
        if (($key == "JavaDevelopmentKit") || ($key == "WriteOnce") || ($key == "Javadatabase") || ($key == "Opendatabase" ) || ($key == "Security")){
            $i++;
        }
    }
    if($i == 5){
        $total++;
    }
    }

It shows a lot of Notice: Undefined variable: key

Answer 1

You are doing wrong in PHP. This is how you can do it.

<?php
if(isset($_POST['category'])){
    //You can also count the total checked by the following line of code
    //$count = count($_POST['category']);
    //or
    //You can loop thru
    $i=0;
    foreach($_POST['category'] as $k=>$v){
        //$k is the number $v hold the value..
        //you can add the counter here like
        $i++;
    }
    if($i <= 2){
        //do your stuff here
    }
}
?>