<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <!-- playing with array_key_exists and isset by: Sharon Tuttle last modified: 2016-03-06 --> <head> <title> array_key_exists vs. isset </title> <meta charset="utf-8" /> <link href="http://users.humboldt.edu/smtuttle/styles/normalize.css" type="text/css" rel="stylesheet" /> <link href="ckbox-play.css" type="text/css" rel="stylesheet" /> </head> <body> <h1> playing with array_key_exists and isset </h1> <?php $conclusion = ""; if (! array_key_exists("bike", $_GET) ) { $conclusion = 'bike was NOT an index in $_GET'; } elseif (! isset($_GET["bike"]) ) { $conclusion = 'bike IS an index in $_GET, but is '. 'not SET'; } else { $conclusion = 'bike IS an index in $_GET, and IS set: ['. htmlspecialchars($_GET["bike"]). ']'; } ?> <p> <?= $conclusion ?> </p> <p> what is in $_GET right now? </p> <ul> <?php foreach ($_GET as $next_form_value) { ?> <li> next value in $_GET is: <?= htmlspecialchars($next_form_value) ?> </li> <?php } ?> </ul> <h2> oh, you want to see GET_$'s keys, also? </h2> <pre> <?php /* BEWARE! NOT SANITIZED! */ print_r($_GET); ?> </pre> <!-- refactoring based on M. Lemos comment on 2016-03-02 --> <?php require_once("328footer-better.html"); ?> </body> </html>