Simplifying multiple echos

问题

I have a full list of timezones in a select menu like so:

<option value="Pacific/Kosrae"> Pacific/Kosrae( +11:00 GMT ) </option>
  <option value="Pacific/Kwajalein"> Pacific/Kwajalein( +12:00 GMT ) </option>
  <option value="Pacific/Majuro"> Pacific/Majuro( +12:00 GMT ) </option>
  <option value="Pacific/Marquesas"> Pacific/Marquesas( -09:30 GMT ) </option>
  <option value="Pacific/Midway"> Pacific/Midway( -11:00 GMT ) </option>

the list goes on forever.

I want to change each of the options into this format:

if($_SESSION['timezone'] == 'Africa/Abidjan') {
echo '<option selected="selected" value="Africa/Abidjan"> Africa/Abidjan( +00:00 GMT ) </option>'; 
} else {
echo '<option value="Africa/Abidjan"> Africa/Abidjan( +00:00 GMT ) </option>';
}

How can I use php to avoid having to copy paste and edit each of the options manually??

回答1:

Store the data in some data structure, and use a loop. For example, using a map from timezone name to offset:

$timezones = array(
    'Pacific/Kosrae' => '+11:00',
    'Pacific/Kwajalein' => '+12:00',
    ...
);

foreach($timezones as $name => $offset) {
    echo "<option value=\"$name\"" . ($name == $_SESSION['timezone'] ? " selected" : "") . ">$name( $offset GMT ) </option>\n";
}

回答2:

Ok, imagine you have a variable containing the form above, let's call it $form and another variable containing i.e. 'Africa/Abidjan' - $timezone.

$pattern = '/="'.str_replace('/', '\/', $timezone).'"/'; # /="Africa\/Abidjan"/
$replacement = '="'.$timezone.'" selected="selected"'; # ="Africa/Abidjan" selected="selected"
$output_form = preg_replace($pattern, $replacement, $form);

Haven't actually tested it, but it should work.

回答3:

$cur_timezone = 'Africa/Abidjan';
$timezones_arr = array ('Pacific/Kosrae','Pacific/Kwajalein',...);
$times_arr = array ('+11:00 GMT', '+12:00 GMT',...);
for ($i = 0; $i < count ($timezones_arr); $i ++) {
  if ($timezones_arr[$i] == $cur_timezone) {
    echo '<option selected="selected" value='$timezones_arr[$i]'>$timezones_arr[$i]($times_arr[$i]) </option>';
  }
  else {
    echo '<option value='$timezones_arr[$i]'>$timezones_arr[$i]($times_arr[$i]) </option>';
  }
}

You must change only variable $cur_timezone. For every element of $timezones_arr must exist elemnt of $times_arr.

回答4:

Ok, you don't have to it with DOM, but since there is already plenty of other answers showing different approaches, here is how to do it with DOM:

function timezoneHelper($selected = NULL)
{   
    $dom = new DOMDocument;
    $dom->formatOutput = TRUE;
    $dom->loadXML('<select/>');
    $dom->documentElement->setAttribute('name', 'timezone-selector');
    $timezones = DateTimeZone::listIdentifiers();
    if(!is_numeric($selected)) {
        $selected = array_search($selected, $timezones);
    }
    foreach($timezones as $id => $timezone) {
        $option = $dom->createElement('option', $timezone);
        $option->setAttribute('value', $id);
        if($id == $selected) {
            $option->setAttribute('selected', 'selected');
        }
        $dom->documentElement->appendChild($option);
        unset($option);
    }
    return $dom->saveXML($dom->documentElement);
}

The above will create a list of timezone identifiers (w\out the GMT diff though. See DateTimeZone::listAbbreviations if you need them) as <option> elements in a <select> element. Unlike your code in the question, the value used for the value attribute is the numeric offset in the array returned by DateTimeZone::listIdentifiers(); instead of the timezone identifier itself. You can invoke the helper with the timezone identifier or the numeric ID though, e.g.

echo timezoneHelper('551');
// or
echo timezoneHelper('Zulu');

would both markup

 <option value="551" selected="selected">Zulu</option>

with the selected attribute in the list returned.

来源：https://stackoverflow.com/questions/3132955/simplifying-multiple-echos