PHP timezone dropdown

readme.md

Drop down of all timezones, grouped by Region, + a list of manual UTC offsets

timezones_dropdown.php

<?php

// Continent list
$continent = array(
    'Africa'     => DateTimeZone::AFRICA,
    'America'    => DateTimeZone::AMERICA,
    'Antarctica' => DateTimeZone::ANTARCTICA,
    'Aisa'       => DateTimeZone::ASIA,
    'Atlantic'   => DateTimeZone::ATLANTIC,
    'Europe'     => DateTimeZone::EUROPE,
    'Indian'     => DateTimeZone::INDIAN,
    'Pacific'    => DateTimeZone::PACIFIC,
);

// Timezones per continents
$timezones = array();
foreach ($continent as $name => $mask) {
    $zones = DateTimeZone::listIdentifiers($mask);
    foreach($zones as $timezone) {
		// Lets sample the time there right now
		$time = new DateTime(NULL, new DateTimeZone($timezone));

		// For Americans and their so called "millitary time"
		$ampm = $time->format('H') > 12 ? ' ('. $time->format('g:i a'). ')' : '';

		// Remove region name and add a sample time
		$timezones[$name][$timezone] = substr($timezone, strlen($name) + 1) . ' - ' . $time->format('H:i') . $ampm;
	}
}

// Manual UTC offset
$offset_range = array(
    -12,     -11.5,    -11,     -10.5,    -10,     -9.5,     -9,
    -8.5,    -8,       -7.5,    -7,       -6.5,    -6,       -5.5,
    -5,      -4.5,     -4,      -3.5,     -3,      -2.5,     -2,
    -1.5,    -1,       -0.5,    0,        0.5,     1,        1.5,
    2,       2.5,      3,       3.5,      4,       4.5,      5,       5.5,
    5.75,    6,        6.5,     7,        7.5,     8,        8.5,
    8.75,    9,        9.5,     10,       10.5,    11,       11.5,
    12,      12.75,    13,      13.75,    14,
);
foreach( $offset_range as $offset ) {
    if ( 0 <= $offset ) {
        $offset_name = '+' . $offset;
    } else {
        $offset_name = (string) $offset;
    }

    $offset_value = $offset_name;
    $offset_name  = str_replace( array( '.25', '.5', '.75' ), array( ':15', ':30', ':45' ), $offset_name );
    $offset_name  = 'UTC' . $offset_name;
    $offset_value = 'UTC' . $offset_value;

    $timezones['UTC'][$offset_value] = $offset_name;
}


// View
print '<label>Select Your Timezone</label><select id="timezone">';
print '<option name="">(select)</option>';
foreach($timezones as $region => $list)
{
	print '<optgroup label="' . $region . '">' . "\n";
	foreach($list as $timezone => $name)
	{
		print '<option name="' . $timezone . '">' . $name . '</option>' . "\n";
	}
	print '<optgroup>' . "\n";
}
print '</select>';