&& combined with !=

[douglaswalker 67]

Hi there,

I have come across a curious coding issue which may just be curious to me... but I wondered if any\one has come across it and could shed any light.

Ok here goes.... the code below

works as expected and stops the code running on checkout_shipping.php, checkout_payment.php and checkout_confirmation.php

 function isEnabled() {
    	global $PHP_SELF;
    	if (($PHP_SELF == 'checkout_shipping.php')|| ($PHP_SELF == 'checkout_payment.php') || ($PHP_SELF == 'checkout_confirmation.php'))  {
    	    $this->enabled = false;
    	}
  	return $this->enabled;
	}

Then i tried the code below to allow the code to run on checkout_shipping.php, checkout_payment.php and checkout_confirmation.php but no where else

however it does not work and the code runs nowhere.

 function isEnabled() {
    	global $PHP_SELF;
    	if (($PHP_SELF != 'checkout_shipping.php')|| ($PHP_SELF != 'checkout_payment.php') || ($PHP_SELF != 'checkout_confirmation.php'))  {
    	    $this->enabled = false;
    	}
  	return $this->enabled;
	}

then I tried this (see below and it works perfectly. Only allowing the code to run on  checkout_shipping.php, checkout_payment.php and checkout_confirmation.php

 function isEnabled() {
    	global $PHP_SELF;
    	if (($PHP_SELF != 'checkout_shipping.php')&& ($PHP_SELF != 'checkout_payment.php') && ($PHP_SELF != 'checkout_confirmation.php'))  {
    	    $this->enabled = false;
    	}
  	return $this->enabled;
	}

I thought that if I added && then all the conditions had to be correct at the same time?

Why does the || not work?

Any light that can be shed would be appreciated 

[Hotclutch 191]

If you want to use || this logic will suffice:

    function isEnabled() {
      global $PHP_SELF;
      
    	if (($PHP_SELF == 'checkout_shipping.php') || ($PHP_SELF == 'checkout_payment.php') || ($PHP_SELF == 'checkout_confirmation.php')) {
  	    return $this->enabled;
	    }
	 }

 

[douglaswalker 67]

Oh my god.. I am stupid

thank-you

 

[burt 5,612]

Keep it more simple and allow the possibility to easier add pages in;

$pages = array('checkout_shipping.php', 'checkout_payment.php', 'checkout_confirmation.php');

if (!in_array($PHP_SELF, $pages)) {
  // is NOT a page in $pages
}

if (in_array($PHP_SELF, $pages)) {
  // IS a page in $pages
}

G

[douglaswalker 67]

nice... thank-you

[MrPhil 648]

Basic Boolean logic:  not(A or B) is the same as (not A) and (not B). Likewise not(A and B) is the same as (not A) or (not B).

By the way, == and != are higher precedence than || or &&, so the inner () can safely be omitted. Some coders prefer to explicitly give them just so things are perfectly clear to the next reader.