How to check if an array contains all false values?

Question

How to check if an array contains all false values?

$arr  = array(false, false, false);
$arr2 = array(true, false, false, 123);

check_false_array($arr);
true
check_false_array($arr2);
false

edit: not only true/false values are allowed

@George Why shouldn't it be? It shows exactly how to check, that an array only contains the same values — Rizier123, Jul 22 '15 at 12:29
Array contains the same values vs Array contains the same of specific value, no? — George, Jul 22 '15 at 12:30
I agree with George since this goes deeper as working with booleans changes this question enough to be considered different. — John Conde, Jul 22 '15 at 12:31
@George wow only to change: `if (count(array_unique($allvalues)) === 1 && end($allvalues) === 'true') {` to `if (count(array_unique($allvalues)) === 1 && end($allvalues) === FALSE) {` makes it a different question? — Rizier123, Jul 22 '15 at 12:32
Well, yeah.. Having said that, the OP has shown no (research) effort of their own, so if anything it should be closed as off-topic. — George, Jul 22 '15 at 12:35
@George So you really want to tell me, that changing one value in the entire code makes it not a duplicate?! — Rizier123, Jul 22 '15 at 12:36
IMO yeah. While that change to get the solution might be obvious to you or me, it might not be to the person asking the question. — George, Jul 22 '15 at 12:38
@George So you wouldn't close any question with this: http://stackoverflow.com/a/8881719/3933332 only because they have to change one freaking value. So we would end up with thousands of `in_array()` answers just with different values. I completely disagree here, but don't want to discuss here in the comments, so I will end it here. — Rizier123, Jul 22 '15 at 12:44

John Conde · Accepted Answer · 2015-07-22T12:33:00.033

3

Use array_filter() and empty(). array_filter() will remove all false values and if empty() returns true you have all false values.

function check_false_array(array $array) {
    return empty(array_filter($array, 'strlen'));
}

var_export(check_false_array(array(false, false, false)));
echo "\n";
var_export(check_false_array(array(false, true, false)));
echo "\n";
var_export(check_false_array(array(0,0,0)));

Demo

If you want 0 to be considered false just remove the callback to 'strlen' in array_filter().

Demo

edited Jul 22 '15 at 12:33

answered Jul 22 '15 at 12:23

John Conde

217,595
99
455
496

What if the array is `array(0,0,0)`? – Sougata Bose Jul 22 '15 at 12:25
@b0s3 *"all false values"* would imply *any* falsey value - maybe that's just me. – George Jul 22 '15 at 12:29
If you pass `'strlen'` to `array_filter()` it will correctly handle this. See the demo. – John Conde Jul 22 '15 at 12:29
@George `array(false, false) !== array(false, 0)` OR `false !== 0`. AFAIK. – Sougata Bose Jul 22 '15 at 12:32
@b0s3 That wasn't my argument. – George Jul 22 '15 at 12:34
@George I am just pointing out the chances as OP did not mention this. :) – Sougata Bose Jul 22 '15 at 12:35

Sougata Bose · Answer 2 · 2015-07-22T12:30:22.027

0

You can use array_filter with a callback for identical match to false & empty to check.

$arr  = array(false, false, false);
$check = array_filter($arr, function($x) {
  return ($x !== false);
});

if(empty($check)) // $check will be empty if all the value is false (only false)

edited Jul 22 '15 at 12:30

answered Jul 22 '15 at 12:24

Sougata Bose

31,517
8
49
87

score -1 · Answer 3 · answered Jul 22 '15 at 12:23

these two functions will check for what you need, assuming the arrays can only have "true" or "false" and nothing else

function isFalseArray($arr){
    foreach($arr as $a){
        if($a == "true")
           return false;
    }
    return true;
}

function isTrueArray($arr){
    foreach($arr as $a){
        if($a == "false")
           return false;
    }
    return true;
}

How to check if an array contains all false values?

3 Answers3