PHP Count Number of True Values in a Boolean Array

Question

I have an associative array in which I need to count the number of boolean true values within.

The end result is to create an if statement in which would return true when only one true value exists within the array. It would need to return false if there are more then one true values within the array, or if there are no true values within the array.

I know the best route would be to use count and in_array in some form. I'm not sure this would work, just off the top of my head but even if it does, is this the best way?

$array(a->true,b->false,c->true)    

if (count(in_array(true,$array,true)) == 1)
{
    return true
}
else
{
    return false
}

Jonathan Kuhn · Accepted Answer · 2022-03-17T23:38:34.887

I would use array_filter.

$array = array(true, true, false, false);
echo count(array_filter($array));
//outputs: 2

Array_filter will remove values that are false-y (value == false). Then just get a count. If you need to filter based on some special value, like if you are looking for a specific value, array_filter accepts an optional second parameter that is a function you can define to return whether a value is true (not filtered) or false (filtered out).

Frédéric Clausset · Answer 2 · 2013-05-07T22:27:52.590

14

Since TRUE is casted to 1 and FALSE is casted to 0. You can also use array_sum

$array = array('a'=>true,'b'=>false,'c'=>true);
if(array_sum($array) == 1) {
    //one and only one true in the array
}

From the doc : "FALSE will yield 0 (zero), and TRUE will yield 1 (one)."

edited May 07 '13 at 22:27

answered May 07 '13 at 22:16

Frédéric Clausset

1,086
6
9

This would have worked just as well, thanks for the provision! – ThatTechGuy May 07 '13 at 22:36
1

This is actually a pretty clever solution. Kudos! – lgomezma Sep 05 '16 at 14:47

score 3 · Answer 3 · answered May 07 '13 at 21:19

3

Try this approach :

<?php
$array = array(1, "hello", 1, "world", "hello");
print_r(array_count_values($array));
?>

Result :

Array
(
   [1] => 2
   [hello] => 2
   [world] => 1
)

Documentation

answered May 07 '13 at 21:19

ROMMEL

524
2
10

1

This works for strings/integers, however they are looking for boolean values. So this will throw an E_WARNING for every element not a string/int. Example: http://codepad.viper-7.com/zPTF0U – Jonathan Kuhn May 07 '13 at 21:26

score 0 · Answer 4 · answered May 07 '13 at 21:17

0

like this?

$trues = 0;
foreach((array)$array as $arr) {
   $trues += ($arr ? 1 : 0);
}
return ($trues==1);

answered May 07 '13 at 21:17

score 0 · Answer 5 · answered May 07 '13 at 21:19

0

Have you tried using array_count_values to get an array with everything counted? Then check how many true's there are?

answered May 07 '13 at 21:19

Ruben Weerts

313
1
6

PHP Count Number of True Values in a Boolean Array

5 Answers5

Linked