PHP case-insensitive in_array function

Question

Is it possible to do case-insensitive comparison when using the in_array function?

So with a source array like this:

$a= array(
 \'one\'         


        

Answer 1

$a = [1 => 'funny', 3 => 'meshgaat', 15 => 'obi', 2 => 'OMER'];  

$b = 'omer';

function checkArr($x,$array)
{
    $arr = array_values($array);
    $arrlength = count($arr);
    $z = strtolower($x);

    for ($i = 0; $i < $arrlength; $i++) {
        if ($z == strtolower($arr[$i])) {
            echo "yes";
        }  
    } 
};

checkArr($b, $a);

Answer 2

$user_agent = 'yandeX';
$bots = ['Google','Yahoo','Yandex'];        
        
foreach($bots as $b){
     if( stripos( $user_agent, $b ) !== false ) return $b;
}

Answer 3

The obvious thing to do is just convert the search term to lowercase:

if (in_array(strtolower($word), $array)) { 
  ...

of course if there are uppercase letters in the array you'll need to do this first:

$search_array = array_map('strtolower', $array);

and search that. There's no point in doing strtolower on the whole array with every search.

Searching arrays however is linear. If you have a large array or you're going to do this a lot, it would be better to put the search terms in key of the array as this will be much faster access:

$search_array = array_combine(array_map('strtolower', $a), $a);

then

if ($search_array[strtolower($word)]) { 
  ...

The only issue here is that array keys must be unique so if you have a collision (eg "One" and "one") you will lose all but one.

Answer 4

you can use preg_grep():

$a= array(
 'one',
 'two',
 'three',
 'four'
);

print_r( preg_grep( "/ONe/i" , $a ) );

Answer 5

Say you want to use the in_array, here is how you can make the search case insensitive.

Case insensitive in_array():

foreach($searchKey as $key => $subkey) {

     if (in_array(strtolower($subkey), array_map("strtolower", $subarray)))
     {
        echo "found";
     }

}

Normal case sensitive:

foreach($searchKey as $key => $subkey) {

if (in_array("$subkey", $subarray))

     {
        echo "found";
     }

}

Answer 6

function in_arrayi($needle, $haystack) {
    return in_array(strtolower($needle), array_map('strtolower', $haystack));
}

Source: php.net in_array manual page.