How to store data of same name in a session in php?

Question

I want my user to be able to submit a form, and then those form values are stored in a session. The form posts back to itself, so how can I store the data time and time again in a session?

<form action="addPerson.php" method="post">
    <input required="required" placeholder="Name" name="personname"/>       
    <label for="gender">Male or Female?</label> 
    <select id="gender" name="gender">      
        <option value="f">Female</option>
        <option value="m">Male</option>
    </select>


<button type="submit">add person</button>
</form>

So I was thinking:

$_SESSION["personname"] = $_POST['personname'];
$_SESSION["persongender"] = $_POST['gender'] ;

But this would get replaced every time a new form is posted.

Answer 1

$_SESSION['people'][] = array(
    'personname' => $_POST['personname'],
    'persongender' => $_POST['gender']
);

Answer 2

What about:

$_SESSION["personname"][] = $_POST['personname'];
$_SESSION["persongender"][] = $_POST['gender'] ;

The values are stored in an array that way.

Or:

$_SESSION['persons'][] = array( $_POST['personname'], $_POST['gender']);

Answer 3

I would do it like this.

$_SESSION[] = array("personname" => $_POST['personname'], 
                    "persongender" => $_POST['gender']) ;

This way you get a multidemensional array and you can loop through it if you want to access an old value.