Php ternary statement

Question

Hi i was recently looking over a shopping cart paginator class, trying to understand their code so i could build my own paginator when i came across the following line of code. It resembles a ternary statement but is written in a way that i have never seen before. I would google it but i wouldn't know what to google. Could someone please tell me what this is how it works and what it is called so i can do a search for it and learn more.

    return ($output ? '<div class="' . $this->style_links . '">' . $output . '</div>' : '') 
. '<div class="' . $this->style_results . '">' . sprintf($this->text, ($total) ? (($page - 1) * $limit) + 1 : 0, ((($page - 1) * $limit) > ($total - $limit)) ? $total : ((($page - 1) * $limit) + $limit), $total, $num_pages) . '</div>';

Just let me know if this is enough code to go on Thanks Andrew

Answer 1

expression ? runs if true : runs if false;

More here

 http://www.johnhok.com/2008/02/23/php-tip-tertiary-operator/

In your case:

$output ? '<div class="' . $this->style_links . '">' . $output . '</div>' : ''

If $output variable is not empty then following is return otherwise empty '' string is returned.

<div class="' . $this->style_links . '">' . $output . '</div>'

Same is the case with other tertiary operators used in your code.

Answer 2

Nice... It is just a regular conditional operator (well, 3 of them, along with some concatenation).

If you reformat it, it gets a bit clearer:

$output = $output ? '<div class="' . $this->style_links . '">' . $output . '</div>' : '';

$min = $total ? (($page - 1) * $limit) + 1 : 0;
$max = (($page - 1) * $limit) > ($total - $limit) ? $total : ((($page - 1) * $limit) + $limit);

$output .= '<div class="' . $this->style_results . '">'
    . sprintf($this->text, $min, $max, $total, $num_pages)
    . '</div>';

return $output;

Answer 3

It is called conditional operator and I would consider this to be an abuse of it. Conditional operators can be useful in reducing short if-else constructs into one statement without effecting the readability of the code.

if(a == b)
    c = d;
else
    c = e;
//can be written as:
c = a == b ? d : e;

The given code can be written as:

return ($output ? 
            '<div class="' . $this->style_links . '">' . $output . '</div>'
         : '') . 
    '<div class="' . $this->style_results . '">' . 
    sprintf($this->text, 
        ($total) ? 
            (($page - 1) * $limit) + 1 
          : 0, 
        ((($page - 1) * $limit) > ($total - $limit)) ? 
            $total 
          : ((($page - 1) * $limit) + $limit), 
        $total, $num_pages) . '</div>';

And is equivalent to:

if($output)
    $str = '<div class="' . $this->style_links . '">' . $output . '</div>';
else
    $str = '';

$str .= '<div class="' . $this->style_results . '">';

if($total)
    $first = (($page - 1) * $limit) + 1;
else
    $first = 0;

if((($page - 1) * $limit) > ($total - $limit))
    $second = $total;
else
    $second = ((($page - 1) * $limit) + $limit);

$str .= sprintf($this->text, $first, $second, $total, $num_pages);
$str .= '</div>';