What does this PHP print?

By Ovid on March 26, 2013 4:48 PM

Via this blog entry which I'm sure some of you have seen before, the following PHP prints "horse".

<?php
  $arg = 'T';                                                                                                                
  $vehicle = ( ( $arg == 'B' ) ? 'bus' :
               ( $arg == 'A' ) ? 'airplane' :
               ( $arg == 'T' ) ? 'train' :
               ( $arg == 'C' ) ? 'car' :
               ( $arg == 'H' ) ? 'horse' :
               'feet' );
  echo $vehicle;
?>

No fun shooting fish (or a horse) in a barrel, but wow. Just wow.

10 comments

10 Comments

Joel Berger | March 26, 2013 7:05 PM

Wow! Icky ick. It took me a long time to figure out what the heck was going on. Now that I get it, you can get 'feet' by changing 'car' to ''. Yeah that's logical.

KneLL | March 26, 2013 10:43 PM

But why such result? Could anyone explain?

brian d foy | March 27, 2013 2:47 AM

I'm surprised I had so much trouble making that code do the expected thing, so I had to explain it all.

To be fair, the PHP manual acknowledges this problem and tells people not to nest them. It's not like Perl has a similar problem with a certain 5.10 feature.

Aristotle replied to comment from brian d foy | March 27, 2013 5:48 AM

That would be a fair point if umpteen other languages hadn’t already gotten the ternary operator right. To my knowledge, the same cannot be said of the smart match operator.

Joel Berger | March 27, 2013 1:04 PM

Luckily for PHP, if they ever want to correct their mistake, they need only do so, and then indicate the breaking change by increasing their major version number. Smartmatch however...

Toby Inkster replied to comment from brian d foy | March 27, 2013 3:51 PM

Also PHP has had a "switch" statement since forever. Whatsmore, the optional braces make an if/elseif/.../else chain in PHP much more appealing than it is in Perl.

Aristotle replied to comment from Joel Berger | March 27, 2013 9:22 PM

Smartmatch however…

… “will take two major versions to fix”, is that the missing part of your sentence, Joel? :-)

ugexe | March 27, 2013 10:46 PM


<?php
    if (0 == "zero") {
        print "welp\n";
    }
?>

welp

Robin | March 29, 2013 10:35 AM


<?php
    $a = array( 'a' => 1, 'b' => 2);
    $b = array( 'b' => 1, 'a' => 2);

    print '$a < $b: ' . ($a < $b ? 'true' : 'false') . "\n";
    print '$a > $b: ' . ($a > $b ? 'true' : 'false') . "\n";
?>

$a is simultaneously greater than and less than $b.

Toby Inkster replied to comment from ugexe | March 29, 2013 8:22 PM

#!perl
if (0 == "zero") {
  print "welp\n";
}

In both the PHP and Perl versions, it's down to a poor choice of operator. In Perl you probably meant 0 eq "zero"; in PHP you probably wanted 0 === "zero".

About Ovid

Freelance Perl/Testing/Agile consultant and trainer. See http://www.allaroundtheworld.fr/ for our services. If you have a problem with Perl, we will solve it for you. And don't forget to buy my book! http://www.amazon.com/Beginning-Perl-Curtis-Poe/dp/1118013840/

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