How can I determine the difference between false and 0?

Question

I have a variable which always contains one of these two cases:

My variable in reality is this:

$index = array_search(1, array_column($var, 'box'));
//=> the output could be something like these: false, 0, 1, 2, ...

Now I want to detect $index is false or anything else. How can I implement such a condition?

It should be noted none of these doesn't work:

if ( empty($index) )   { }
if ( !isset($index) )  { }
if ( is_null($index) ) { }

And I want this condition:

if ( ? ) { // $index is false } else { // $index is a number (even 0) }

@Rizier123 emm, interesting, I thought it will be much harder. — stack, Apr 18 '16 at 11:53

kainaw · Answer 1 · 2016-04-18T11:56:07.903

1

Use the === operator...

if(false == 0)

That will cast 0 to false and you get false == false

if(false === 0)

That does not cast and you get false compared to zero, which is not the same.

For not equal to, use !== instead of ===

edited Apr 18 '16 at 11:56

answered Apr 18 '16 at 11:53

kainaw

if false === 0 is always false because you compare a boolean against an integer and it is never the same – B001ᛦ Apr 18 '16 at 11:54
@bub Correct. I was pointing out that false===0 is false while false==0 is true. – kainaw Apr 18 '16 at 11:55

score 1 · Accepted Answer · edited May 23 '17 at 12:16

You can use the PHP identical operator ===:

if (false === 0)

This will return false if they are of the same type. Unlike == where type juggling occurs, false is not identical to 0.

if ($index === false) { 
    // $index is false
} else {
    // $index is a number (even 0)
}

More information on the difference between the identical operator === and the comparison operator ==: How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?

2 Answers2