Does PHP have an equivalent of C/C++'s #ifdef?

Question

I\'m trying to define a constant, but I don\'t want to redefine it if it\'s already been defined. Here\'s a C sample:

#ifndef BASEPATH
#define BASEPATH /mnt/www         


        

Answer 1

if(!defined('BASEPATH')) {
    define('BASEPATH', '/mnt/www');
}

http://us3.php.net/manual/en/function.defined.php