PHP 不区分大小写的 in_array 函数

PHP case-insensitive in_array function

提问by leepowers

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

使用该in_array函数时是否可以进行不区分大小写的比较？

So with a source array like this:

因此，对于这样的源数组：

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

The following lookups would all return true:

以下查找都将返回 true：

in_array('one', $a);
in_array('two', $a);
in_array('ONE', $a);
in_array('fOUr', $a);

What function or set of functions would do the same? I don't think in_arrayitself can do this.

什么功能或一组功能会做同样的事情？我不认为in_array自己可以做到这一点。

采纳答案by ghostdog74

you can use preg_grep():

你可以使用preg_grep()：

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

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

回答by cletus

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

显而易见的事情就是将搜索词转换为小写：

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

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

当然，如果数组中有大写字母，您需要先执行此操作：

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

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

并搜索那个。strtolower每次搜索都对整个数组进行操作是没有意义的。

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 muchfaster access:

然而，搜索数组是线性的。如果你有一个大的数组或你打算这样做了很多，这将是更好地把搜索条件在阵列的关键，因为这将是很多快速访问：

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

then

然后

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.

这里唯一的问题是数组键必须是唯一的，因此如果发生冲突（例如“一”和“一”），您将丢失除一个之外的所有键。

回答by Tyler Carter

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

From Documentation

从文档

回答by Gazler

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

Source: php.net in_array manual page.

来源：php.net in_array 手册页。

回答by Mike Q

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

假设您想使用 in_array，这里是如何使搜索不区分大小写的方法。

Case insensitive in_array():

in_array() 不区分大小写：

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

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

}

Normal case sensitive:

正常区分大小写：

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

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

     {
        echo "found";
     }

}

回答by Alex

The above is correct if we assume that arrays can contain only strings, but arrays can contain other arrays as well. Also in_array() function can accept an array for $needle, so strtolower($needle) is not going to work if $needle is an array and array_map('strtolower', $haystack) is not going to work if $haystack contains other arrays, but will result in "PHP warning: strtolower() expects parameter 1 to be string, array given".

如果我们假设数组只能包含字符串，那么上面是正确的，但数组也可以包含其他数组。此外 in_array() 函数可以接受 $needle 的数组，因此如果 $needle 是数组，则 strtolower($needle) 将不起作用，如果 $haystack 包含其他数组，则 array_map('strtolower', $haystack) 将不起作用数组，但会导致“PHP 警告：strtolower() 期望参数 1 为字符串，给定数组”。

Example:

例子：

$needle = array('p', 'H');
$haystack = array(array('p', 'H'), 'U');

So i created a helper class with the releveant methods, to make case-sensitive and case-insensitive in_array() checks. I am also using mb_strtolower() instead of strtolower(), so other encodings can be used. Here's the code:

所以我用相关方法创建了一个辅助类，以进行区分大小写和不区分大小写的 in_array() 检查。我还使用 mb_strtolower() 而不是 strtolower()，因此可以使用其他编码。这是代码：

class StringHelper {

public static function toLower($string, $encoding = 'UTF-8')
{
    return mb_strtolower($string, $encoding);
}

/**
 * Digs into all levels of an array and converts all string values to lowercase
 */
public static function arrayToLower($array)
{
    foreach ($array as &$value) {
        switch (true) {
            case is_string($value):
                $value = self::toLower($value);
                break;
            case is_array($value):
                $value = self::arrayToLower($value);
                break;
        }
    }
    return $array;
}

/**
 * Works like the built-in PHP in_array() function — Checks if a value exists in an array, but
 * gives the option to choose how the comparison is done - case-sensitive or case-insensitive
 */
public static function inArray($needle, $haystack, $case = 'case-sensitive', $strict = false)
{
    switch ($case) {
        default:
        case 'case-sensitive':
        case 'cs':
            return in_array($needle, $haystack, $strict);
            break;
        case 'case-insensitive':
        case 'ci':
            if (is_array($needle)) {
                return in_array(self::arrayToLower($needle), self::arrayToLower($haystack), $strict);
            } else {
                return in_array(self::toLower($needle), self::arrayToLower($haystack), $strict);
            }
            break;
    }
}
}

回答by Jake

I wrote a simple function to check for a insensitive value in an array the code is below.

我编写了一个简单的函数来检查数组中的不敏感值，代码如下。

function:

功能：

function in_array_insensitive($needle, $haystack) {
   $needle = strtolower($needle);
   foreach($haystack as $k => $v) {
      $haystack[$k] = strtolower($v);
   }
   return in_array($needle, $haystack);
}

how to use:

如何使用：

$array = array('one', 'two', 'three', 'four');
var_dump(in_array_insensitive('fOUr', $array));

回答by Carlos Coelho

/**
 * in_array function variant that performs case-insensitive comparison when needle is a string.
 *
 * @param mixed $needle
 * @param array $haystack
 * @param bool $strict
 *
 * @return bool
 */
function in_arrayi($needle, array $haystack, bool $strict = false): bool
{

    if (is_string($needle)) {

        $needle = strtolower($needle);

        foreach ($haystack as $value) {

            if (is_string($value)) {
                if (strtolower($value) === $needle) {
                    return true;
                }
            }

        }

        return false;

    }

    return in_array($needle, $haystack, $strict);

}


/**
 * in_array function variant that performs case-insensitive comparison when needle is a string.
 * Multibyte version.
 *
 * @param mixed $needle
 * @param array $haystack
 * @param bool $strict
 * @param string|null $encoding
 *
 * @return bool
 */
function mb_in_arrayi($needle, array $haystack, bool $strict = false, ?string $encoding = null): bool
{

    if (null === $encoding) {
        $encoding = mb_internal_encoding();
    }

    if (is_string($needle)) {

        $needle = mb_strtolower($needle, $encoding);

        foreach ($haystack as $value) {

            if (is_string($value)) {
                if (mb_strtolower($value, $encoding) === $needle) {
                    return true;
                }
            }

        }

        return false;

    }

    return in_array($needle, $haystack, $strict);

}

回答by omer

$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);

回答by user1077915

• in_array accepts these parameters : in_array(search,array,type)
• if the search parameter is a string and the type parameter is set to TRUE, the search is case-sensitive.
• so in order to make the search ignore the case, it would be enough to use it like this :

• in_array 接受这些参数： in_array(search,array,type)
• 如果搜索参数是字符串并且类型参数设置为 TRUE，则搜索区分大小写。
• 所以为了让搜索忽略大小写，像这样使用它就足够了：

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

$a = array( '一', '二', '三', '四');

$b = in_array( 'ONE', $a, false );

$b = in_array( 'ONE', $a, false );