How to validate an array in a PHP form?

Question

I'm fairly new to php and was wondering how do I validate the array for the states and where do I place the php code at? I already did the address part but I'm stuck at the states part.

Here is the validation code.

if (isset($_POST['contact_info_submitted'])) { // Handle the form.

    $address = mysqli_real_escape_string(htmlentities($_POST['address']));

}

Here is the form code.

<li><label for="address-1">Address 1: </label><input type="text" name="address-1" id="address-1" size="25" class="input-size" value="<?php if (isset($_POST['address'])) echo $_POST['address']; ?>" /></li>

<li><label for="state-province">State/Province: </label>
<?php
echo '<select name="state-province" id="state-province">' . "\n";
    foreach($state_options as $option) {
        if ($option == $state) {
            echo '<option value="' . $option . '" selected="selected">' . $option . '</option>' . "\n";
            } else {
              echo '<option value="'. $option . '">' . $option . '</option>'."\n";
            }
        }
            echo '</select>';

?>
</li>
<li><input type="submit" name="submit" value="Save Changes" class="save-button" />
    <input type="hidden" name="contact_info_submitted" value="true" />

Answer 1

If you're wondering how to check if someone submitted a valid value for state just check to see if there value they posted is in your array of states. If it's not there it's not valid:

if (!in_array($_POST['state-province'], $state_options)) {
    // not valid
}

If you're just trying to store in the a database like the other form values it's no different then any text field:

if (isset($_POST['contact_info_submitted'])) { // Handle the form.
    $state= mysqli_real_escape_string($_POST['state-province']);
}