Check if value is the only thing in an array using php - php

Question

I have an array that looks like this...
Array
(
[0] => red
[1] => red
[2] => red
)
I am trying to check if red is the only thing in the array, I would want it to fail if the array looked like this...
Array
(
[0] => red
[1] => yellow
[2] => red
)

Answer 1

Using array_unique() you can just count the number of occurances returned. If its > 1 you have not got all red
<?php
$array = ['red','red','red'];
if ( count(array_unique($array)) == 1 && array_unique($array)[0] == 'red' ) {
echo 'all red';
} else {
echo 'error';
}

Answer 2

Use combination of count() and array_filter() to find count of unwanted item in array.
$invalidItems = count(array_filter($arr, function($item){
return $item != 'red';
}));
if ($invalidItems)
echo 'invalid';
else
echo 'valid';
Check result in demo

Answer 3

You could just use array_unique() to get it to remove duplicates and then count the size of the remaining list, you can also then check that the 1 value is whatever value your expecting...
$unique = array_unique($a);
if ( count($unique) == 1 && $unique[0] == 'value' ) {
}

Answer 4

You can do it like this:
$array = [
'foo',
'foo',
'foo'
];
$values = array_count_values($array);
$count = count($array);
if (!empty($values['foo']) && $count === $values['foo']) {
echo 'all array values match foo';
} else {
echo 'foo not found in array';
}
here we count values in the array vs the overall count of the array
Edit: The only problem is, you have to know the value you're comparing against to get the result
Edit 2: Addressing issue raised by MickMackusa:
and the other problem is, if the value that you are looking for doesn't exist at all in the input array, then it won't exist as a key in the $values array and thus your code will generate a Notice. ...not good.

Answer 5

You don't need more than one function call to check for non-red values exist. The following checks if there are any non-red elements.
Codes (Demo)
$array = ['red','red','red'];
var_export(!array_diff($array, ['red'])); // true
echo "\n";
var_export(!array_filter($array, function($v){return $v !== 'red';})); // true
$array = ['red','yellow','red'];
var_export(!array_diff($array, ['red'])); // false
echo "\n";
var_export(!array_filter($array, function($v){return $v !== 'red';})); // false
I think array_filter() is a more "direct" technique, but array_diff() doesn't need a custom function so it is arguably easier to read.
If your coding logic must require the existence of red as well as disqualify arrays that contain a non-red element, then just add a condition that checks if the array has any elements. (more precise demo)
And for best performance, use a loop with a break -- this way you don't have to iterate the entire array unless absolutely necessary. Early breaks are a good thing. Demo
$array = ['red','yellow','red'];
$result = true;
foreach ($array as $value) {
if ($value != 'red') {
$result = false;
break;
}
}

Answer 6

Check if red is there, then remove duplicate values and check that there is only one:
if(in_array('red', $array) && (count(array_unique($array)) == 1)) {
// yes
}

Answer 7

Old school foreach (all) red or dead:
<?php
$things = ['red', 'white', 'blue'];
foreach($things as $colour)
if ($colour !== 'red')
throw new Exception('dead');