17th DEGREE

I came across an interesting quirk in PHP today. The way a nested ternary operator is evaluated in PHP is unlike that of any other language I’ve come across: left to right.

Ex:

<?php
$test = 'one';
echo $test == 'one' ? 'one' :  $test == 'two' ? 'two' : 'three';
?>

What do you suppose that prints? Wrong, the answer is ‘two’. Let’s break this down in how it is working, shall we.

<?php
$test = 'one';
echo $test == 'one' ? 'one' :  $test == 'two' ? 'two' : 'three';
?>

Here, I’ve emphasized the first ternary operation. What PHP will do is evaluate this section and return a value, in this case it is the string ‘one’. The boolean value of the string ‘one’ is true. So, for the second ternary operation, ‘two’ gets selected.

No other language I know of acts like this.

Hopes this help someone one day.

This entry was posted on Wednesday, January 9th, 2008 at 11:34 pm and is filed under Programming, Software. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.