Question

I want to echo variable $a if it is set, or echo variable $b if variable $a was not set.

I tried something, but it doesn’t work as expected:

  <?
    $a = "FOO";
    $b = "BAR";
    $c = $a OR $b;
    echo $c; #output : FOO

    //

    $a = false;
    $b = "BAR";
    $c = $a OR $b;
    echo $c; #output : 
  ?>

I can do it using a function, like

   function F($a,$b) {
      if($a) return $a;
      return $b;
   }

or using this:

   $c = $a ? $a : $b;

but maybe there is a better way to do this. I want the fastest way to accomplish this.

Answer 1

This is the closest to what you are trying to do:

$c = $a ?: $b;

(It is similar to $c = $a || $b in JavaScript.)

Note that this assumes the variables are actually set. If they aren’t set (i.e., don’t exist at all), you should really use isset.