In PHP, is conditional variable substitution possible?

Question

I was wondering if something like the following would be possible in PHP:

<?php echo "Hello {isset($name) ? $name : 'World'}!\n"; ?>

or do I have to do the following?

<?php echo "Hello " . ( isset($name) ? $name : 'World' ) . "!\n"; ?>

In general I prefer substitution over concatenation as I find that string concatenation can make strings harder to read by making them overly long.

The context of which is that I'm deciding which option in a select tag should be selected by default based on a database query.

The full context:

<?php   
echo "
<form action='add_demographics.php' method='post'>
   <table>
      <input type=hidden name=userId value='{$_SESSION['username']}'/>
      <tr><td>User ID:</td><td>{$_SESSION['username']}</td></tr>";

foreach ($inputLabels as $i => $value)
{
    echo "
      <tr>
         <td>{$value['text']}</td>
         <td><select name=$i>";

    foreach ($value["options"] as $optionName => $optionValue)
    {
    echo "
            <option value=$optionValue {($result[$i]==$optionValue ? ' selected=true' : '')}>$optionValue</option>";
    }
    echo "
          </select></td>
      </tr>";
}

echo "
      <tr><td><input type='submit' name='submit' value='Submit' /></td></tr>
   </table>
</form>";
?>

Answer 1

You could do something like this:

$default = "World";
$name = "Dunes";
echo "Hello {${isset($name) ? 'name' : 'default'}}";

UPDATE from webbiedave:

"Don't ever do this as it's absolutely atrocious coding practice to use the ternary operator to reference a throw away variable variable simply to avoid concatenation!

Answer 2

nope, cannot do that. You need to do it outside of the string and concat. The only thing php will do inside a string is look for and evaluate a single $var (no expressions) - if you use double quotes or equivalent heredoc (php does not evaluate vars in single quotes)

Answer 3

No, it isn't possible to do it the way you're asking.

A solution to your specific problem, however, could be to assign a variable at the top of the foreach loop to hold whether or not that option should be selected, then echo that variable as part of your output:

foreach ($value["options"] as $optionName => $optionValue)
{
    $selected = $result[$i] == $optionValue ? "selected='selected'" : "";
    echo "
        <option value=$optionValue $selected>$optionValue</option>";
}

Answer 4

<?
    function is($var,$sub){
      return isset($var)?$var:$sub;
    }

    echo 'Hello, '.is($name,'World').'!\r\n';

    $name = 'Bob';

    echo 'Hello, '.is($name,'World').'!\r\n';
?>

Maybe for short-handing it?

Answer 5

Given what you want to do. I'd say

$string = isset($name) ? $name : 'World';
$result = "Hello $string!\n";
echo $result;

Answer 6

It is never actually required.
Learn to use templates. HTML should be HTML, not some abstract data hardcoded in PHP

<form action='add_demographics.php' method='post'>
   <table>
      <input type=hidden name=userId value='<?=_h($_SESSION['username'])?>'/>
      <tr><td>User ID:</td><td><?=_h($_SESSION['username'])?></td></tr>
<? foreach ($inputLabels as $i => $value): ?>
      <tr>
         <td><?=_h($value['text'])?></td>
         <td><select name="<?=$i?>">
<?   foreach ($value["options"] as $optionName => $optionValue): ?>
            <option value="<?=$optionValue?>" <? if ($result[$i]==$optionValue): ?> selected=true<? endif ?>>
              <?=$optionValue?>
            </option>
<?   endforeach ?>
          </select></td>
      </tr>
<? endforeach ?>
      <tr><td><input type='submit' name='submit' value='Submit' /></td></tr>
   </table>
</form>