使用foreach PHP回显嵌套数组

Question

I have seen many similar issues but none that can help explain my issue. I have an array called cities, with a nested array for the state that has the cities of that state. It looks like this:

$cities = array(
    "ca" => array(
        "los-angeles" => "Los Angeles"
    ),
    "wa" => array(
        "bellingham" => "Bellingham",
        "seattle" => "Seattle",
        "tacoma" => "Tacoma"
    )
);

My PHP code to display many HTML select fields:

<?php
foreach ($cities as $state) {
    echo "<select name='city' id='" . $state . "'>";
    foreach ($state as $city => $name) {
        echo "<option value='" . $city . "'>" . $name . "</option>";
    }
}
?>

The id of the select is always Array. How can I use the key, like "ca" or "wa"?

Answer 1

The problem is that you should be using the array key for the select on the states. Here is my revision of your code. Note that I explicitly have named state_key and state_value as well as city_key and city_value. Naming things explicitly like this helps in debugging. I also added a closing </select> element so the content renders correctly.

foreach ($cities as $state_key => $state_value) {

    echo "<select name='city' id='" . $state_key . "'>";
    foreach ($state_value as $city_key => $city_value) {
        echo "<option value='" . $city_key . "'>" . $city_value . "</option>";
    }
    echo "</select>";

}