check if one of multiple values exists in array - php

Question

For array with single values like
array(2) {
["blue"]=>
int(0)
["red"]=>
int(1)
}
I use this code
<?php
if (array_key_exists('blue',$array))
{
echo "jo";
}
?>
But what code do I need to use for arrays like this
array(2) {
["yellow blue"]=>
int(0)
["red white"]=>
int(1)
}
to check if blue exists?

Answer 1

My take:
if(preg_grep('/blue/', array_keys($array))) { echo 'found'; }
Or if you want to get them:
$matches = preg_grep('/blue/', array_keys($array));
print_r($matches);

Answer 2

$partialKey = 'blue';
$byPartialKey = function ($key) use ($partialKey) {
$parts = explode(' ', $key);
return in_array($partialKey, $parts);
};
$result = array_filter (array_keys($input), $byPartialKey);
$result now contains all keys, that somehow contains $partialKey.

Answer 3

you can do using regular expression
search='blue';
foreach ($array as $key => $value) {
if (preg_match('~'.$search.'~i',$key)) {
echo "jo";
}
}
The \b in the pattern indicates a word boundary, so only the distinct
word "blue" is matched, and not a word partial like "bluegreen"
search='blue';
foreach ($array as $key => $value) {
if (preg_match('/\b'.$search.'\b/i',$key)) {
echo "jo";
}
}
Reference

Answer 4

I would do it like this:
function subkey_exists($string, $array) {
foreach($array as $key => $value) {
$sub_keys = explode(" ", $key);
if(in_array($string,$sub_keys)) {
return true;
}
}
return false;
}
[edit]
updated to your requirements

Answer 5

Yet another array_filter solution :
<?php
function find_keys_like($key, $array) {
return array_filter(array_keys($array), function($k) use (&$key) {
return strpos($k, $key) > -1;
});
}
function array_has_key_like($key, $array) {
return count(find_keys_like($key, $array)) > 0;
}
//test
$a = array('blue' => 1, 'yellow blue' => 2, 'green' => 3);
print_r(find_keys_like('blue', $a));
echo 'blue exists ? ' . (array_has_key_like('blue', $a) ? 'yes' : 'no') . PHP_EOL;
/** result :
Array
(
[0] => blue
[1] => yellow blue
)
blue exists ? yes
*/