PHP parse on page only if defined

Question

I'm trying to define values for certain meta tags on pages of my website, however, I don't necessarily want to define them on every single page.

<?php if ($_SERVER['SCRIPT_NAME'] != '/index.html'): ?>
<meta name="description" content="<?php echo $page_info; ?>"/> }
<?php endif; ?>

As you can see, I have that set to parse on every page but index.html, however, I also want to create the following condition:

Will only parse if $page_info is defined, if not it will not parse anything at all in the php if.

Answer 1

Are you perhaps looking for the isset() function?

<?php if ( isset( $page_info ) && $php_info ): ?>
<meta name="description" content="<?php echo $page_info; ?>"/> }
<?php endif; ?>

Check out the docs for some more info on isset().

isset — Determine if a variable is set and is not NULL

The conditional expression I'm using here checks to see that a variable called $page_info exists and that it is not a "falsy" value. A falsy value is anything that, when converted to a boolean could be considered a false value such as (taken from the docs):

• the boolean FALSE itself
• the integer 0 (zero)
• the float 0.0 (zero)
• the empty string, and the string "0"
• an array with zero elements
• an object with zero member variables (PHP 4 only)
• the special type NULL (including unset variables)
• SimpleXML objects created from empty tags
• Every other value is considered TRUE (including any resource).

---

One other suggestion I can make is to not explicitly test for the page you want to exclude. Rather build an array of all the pages you want to exclude and then use an in_array() call to detect if it is in the list:

$exclude_url = array(
  '/index.html',
  '/about.html'
  '/faq.html'
);

if ( !in_array( $_SERVER[ 'SCRIPT_NAME' ], $exclude_url ) ){
  // page should NOT be excluded!
}