I wrote this function when I was writing my PHP quiz.

mixed highlight_code( string $code, bool $class, bool $return );

More verbose highlight_string. This will either echo or return the code (returns by default). The $class argument will allow you to insert a CSS class in the highlighted PHP's <code> tags. This is useful if you want to highlight code in both a block element and inline elements.

PHP Code:
<?php
    
function highlight_code($code$class=false$return=true)
    {
        if ( empty(
$code) ) return false;

        
$highlight '';
        if ( 
version_compare(PHP_VERSION'4.2.0''<') )
        {
            
ob_start(); // start output buffering to capture contents of highlight
            
highlight_string($code);
            
$highlight ob_get_contents(); // capture output
            
ob_end_clean(); // clear buffer cleanly
        
}
        else
        {
            
$highlight highlight_string($codetrue);
        }
        
        if ( 
$class )
            
$highlight=preg_replace('/<code>/i',"<code class=\"${class}\">"$highlight);

        if ( 
$return )
            return 
$highlight;
        else
            echo 
$highlight;
    }
?>
Created by Curtis Dyer