How strip unused list item tags using PHP

Question

How can I remove list item tags where the fields are empty?

<div>
<ul>
<?php

$a = '<li>'.$a.'</li>';
$b = '<li>'.$b.'</li>';
$c = '<li>'.$c.'</li>';
$d = '<li>'.$d.'</li>';

echo $a;
echo $b;
echo $c;
echo $d;
?>

</ul>
</div>

This is a simplified version

Answer 1

With your example, you should write your php like this:

$result = '';
$result .= '<li>'.$a.'</li>';
$result .= '<li>'.$b.'</li>';
$result .= '<li>'.$c.'</li>';
$result .= '<li>'.$d.'</li>';

echo preg_replace('/<li><\/li>/', '', $result);

Answer 2

<ul>

<?php

$a = isset($a)?"<li>$a</li>":"";
$b = isset($b)?"<li>$b</li>":"";
$c = isset($c)?"<li>$c</li>":"";
$d = isset($d)?"<li>$d</li>":"";

// echo $a.$b.$c.$d; You can do this

echo $a;
echo $b;
echo $c;
echo $d;

?>

</ul>

Hope that helps!

Answer 3

I'd use the ternary operator in a function for this.

<div>
<ul>
<?php
$a =  build_line_item($a);
$b =  build_line_item($b);
$c =  build_line_item($c);
$d =  build_line_item($d);
echo $a;
echo $b;
echo $c;
echo $d;
function build_line_item($var) {
    return !empty($var) ? "<li>{$var}</li>" : '';
}
?>
</ul>
</div>

With this approach you'll only need to make a change in one place if your "empty" definition changes. The current empty rules can be found here, http://php.net/manual/en/function.empty.php.