如何让 in_array() 不区分大小写？

Question

Using this code to check if a value exists in an array but sometimes the array may contain values in uppercase. My lookup value is always in lowercase . I cannot control the array data as its dynamically generated from a database so I need a solution that will ignore the case (uppercase/lowercase).

If the lookup value exists in the array I would like it to match regardless of case sensitivity.

if (in_array('lookupvalue', $array)) {
    // do something
}

output of var_dump($url); :

string(17) "www.paypal.com.au"

output of var_dump($sans); :

array(52) {
  [0]=>
  string(13) "WWW.PAYPAL.AT"
  [1]=>
  string(13) "WWW.PAYPAL.BE"
  [2]=>
  string(13) "WWW.PAYPAL.CA"
  [3]=>
  string(13) "WWW.PAYPAL.CH"
  [4]=>
  string(13) "WWW.PAYPAL.CL"
  [5]=>
  string(13) "WWW.PAYPAL.CN"
  [6]=>
  string(16) "WWW.PAYPAL.CO.ID"
  [7]=>
  string(16) "WWW.PAYPAL.CO.IL"
  [8]=>
  string(16) "WWW.PAYPAL.CO.IN"
  [9]=>
  string(19) "WWW.PAYPAL-MENA.COM"
  [10]=>
  string(16) "WWW.PAYPAL.CO.NZ"
  [11]=>
  string(16) "WWW.PAYPAL.CO.TH"
  [12]=>
  string(16) "WWW.PAYPAL.CO.UK"
  [13]=>
  string(16) "WWW.PAYPAL.CO.ZA"
  [14]=>
  string(17) "WWW.PAYPAL.COM.AR"
  [15]=>
  string(17) "WWW.PAYPAL.COM.AU"
  [16]=>
  string(17) "WWW.PAYPAL.COM.BR"
  [17]=>
  string(17) "WWW.PAYPAL.COM.HK"
  [18]=>
  string(17) "WWW.PAYPAL.COM.MX"
  [19]=>
  string(17) "WWW.PAYPAL.COM.MY"
  [20]=>
  string(17) "WWW.PAYPAL.COM.SA"
  [21]=>
  string(17) "WWW.PAYPAL.COM.SG"
  [22]=>
  string(17) "WWW.PAYPAL.COM.TR"
  [23]=>
  string(17) "WWW.PAYPAL.COM.TW"
  [24]=>
  string(17) "WWW.PAYPAL.COM.VE"
  [25]=>
  string(13) "WWW.PAYPAL.DE"
  [26]=>
  string(13) "WWW.PAYPAL.DK"
  [27]=>
  string(13) "WWW.PAYPAL.ES"
  [28]=>
  string(13) "WWW.PAYPAL.EU"
  [29]=>
  string(13) "WWW.PAYPAL.FI"
  [30]=>
  string(13) "WWW.PAYPAL.FR"
  [31]=>
  string(13) "WWW.PAYPAL.IE"
  [32]=>
  string(13) "WWW.PAYPAL.IT"
  [33]=>
  string(13) "WWW.PAYPAL.JP"
  [34]=>
  string(13) "WWW.PAYPAL.LU"
  [35]=>
  string(13) "WWW.PAYPAL.NL"
  [36]=>
  string(13) "WWW.PAYPAL.NO"
  [37]=>
  string(13) "WWW.PAYPAL.PH"
  [38]=>
  string(13) "WWW.PAYPAL.PL"
  [39]=>
  string(13) "WWW.PAYPAL.PT"
  [40]=>
  string(13) "WWW.PAYPAL.RU"
  [41]=>
  string(13) "WWW.PAYPAL.SE"
  [42]=>
  string(13) "WWW.PAYPAL.VN"
  [43]=>
  string(21) "WWW.THEPAYPALBLOG.COM"
  [44]=>
  string(25) "WWW.PAYPAL-DEUTSCHLAND.DE"
  [45]=>
  string(13) "WWW.PAYPAL.CO"
  [46]=>
  string(17) "WWW.PAYPAL.COM.PE"
  [47]=>
  string(17) "WWW.PAYPAL.COM.PT"
  [48]=>
  string(20) "WWW.PAYPAL-FRANCE.FR"
  [49]=>
  string(20) "WWW.PAYPAL-LATAM.COM"
  [50]=>
  string(23) "WWW.PAYPAL-MARKETING.PL"
  [51]=>
  string(15) "DEMO.PAYPAL.COM"
}

Answer 1

Well if you can make sure, that the search word is always in lowercase, just also put the array in lower case by looping through all values with array_map() and putting them in lowercase with strtolower() , eg

if (in_array('lookupvalue', array_map("strtolower", $array))) {
// do something
}

Answer 2

You can use array_uintersect() for this:

<?php

$haystack = [
  'apple',
  'banana',
  'cherry',
  'PineApple',
  'PEAR',
];

echo (
    array_uintersect(['pineapple'], $haystack, 'strcasecmp')
) ? "found\n" : "not found\n";

It computes the intersection of two arrays by means of a user defined function. You feed it two array, one holding your needle, one being your haystack. As a compare function you simply use php's strcasecmp() function.

So in the end your condition is a one-liner:

if ([] === array_uintersect([$needle], $haystack, 'strcasecmp'))

Which, since this is php, can be simplified to:

if (array_uintersect([$needle], $haystack, 'strcasecmp'))

Obviously you can also define a static function for this:

function in_array_icase($needle, &$haystack) {
    return array_uintersect([$needle], $haystack, 'strcasecmp');
}

$jewelry = ['ring', 'bracelet', 'TaTToo', 'chain'];
if (in_array_icase('tattoo', $jewelry))
    echo "Yea!";

Answer 3

If @Rizier's array_map isn't good for you (don't know why), you can use preg_grep function.

$array = array('Lookupvalue', 'second', 'third');
if (preg_grep('/^lookupVALUE$/i', $array)) {
    echo 'exists';
}

Notice to array_map :
Maybe in Rizier's solution missing strtolower at the first parameter (if you can get it with capitals) to make it completely case-insensitive,

if (in_array(strtolower('LookupVALUE'), array_map('strtolower', $array))) {
    echo 'exists';
}

Answer 4

function searchInArray($text, $array) {
    if (in_array(strtolower($text), array_map("strtolower", $array))) {
    return true;
    }
    return false;
}