November 2002
Intermediate to advanced
640 pages
16h 33m
English
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4.10. Checking if a Key Is in an Array
Problem
You want to know if an array contains a certain key.
Solution
Use isset( )
:
if (isset($array['key'])) { /* there is a value for 'key' in $array */ }Discussion
You can check the definedness of an array element just as you’d for any other variable. See the Introduction to Chapter 5 for more information about the truth value of variables.
See Also
Documentation on isset( ) at
http://www.php.net/isset.
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.