Артем Золин

$arr = [
    '/category0/subcat1/subcat2',
    '/category0/subcat1/subcat4',
    '/category0/subcat5/subcat6',
    '/category2/subcat7/subcat8',
    '/category2/subcat9/subcat10',
    '/category2/subcat11/subcat12',
];

$t = [];
foreach ($arr as $item) {
    $s = explode('/', $item);
    $i = $s[1];
    unset ($s[1], $s[0]);
    if (!$t[$i] ){
        $t[$i] = [];
    }
    foreach ($s as $item){
        array_push ( $t[$i],$item);
    }
}
foreach ($t as &$item){
    $item = array_unique($item);
}
echo('<pre>');
var_dump($t);
var_dump(json_encode($t));
echo('<pre>');

([АВЕКМНОРСТУХавекмнорстухABEKMHOPCTYXabekmhopctyx]\s*\d{3}\s*[АВЕКМНОРСТУХавекмнорстухABEKMHOPCTYXabekmhopctyx]{2}\s*\d{2,3})|([АВЕКМНОРСТУХавекмнорстухABEKMHOPCTYXabekmhopctyx]{2}\s*\d{3}\s*\d{2,3})

print_r(array_replace_recursive($array_1, $array_2, $array_3));

$result = implode(
  '',
  array_unique(
    array_merge(
      preg_split('//u', 'abce', -1, PREG_SPLIT_NO_EMPTY),
      preg_split('//u', 'cbegdy', -1, PREG_SPLIT_NO_EMPTY)
    )
  )
);

$str1.implode('', array_diff(str_split($str2), str_split($str1)))

function unique_multidim_array($array, $key) {
    $temp_array = array();
    $i = 0;
    $key_array = array();
   
    foreach($array as $val) {
        if (!in_array($val[$key], $key_array)) {
            $key_array[$i] = $val[$key];
            $temp_array[$i] = $val;
        }
        $i++;
    }
    return $temp_array;
}

$details = unique_multidim_array($details,'id');

<?php
$strings = [
    'https://site.ru/#top 7 (499) 999-99-99;',
    '7 (499) 999-99-99; https://site.ru/#top',
];

foreach($strings as $str)
{
    print_r(extract_data($str));
}

function extract_data($str)
{
    preg_match('!(https?://[^\s]+)!si', $str, $out);
    $url = $out[1] ?? '';
    
    $str = str_replace($url, '', $str);
    
    $phone = trim(preg_replace('![^0-9\(\)\-\ ]+!si', '', $str));
    
    return [
        'url' => $url,
        'phone' => $phone
    ];
}

Array
(
    [url] => https://site.ru/#top
    [phone] => 7 (499) 999-99-99
)
Array
(
    [url] => https://site.ru/#top
    [phone] => 7 (499) 999-99-99
)

$str = '<offer id="10609" available="true">
        <price>847</price>
        <currencyId>RUB</currencyId>
        <categoryId>787</categoryId>
    </offer>
    <offer id="10617" available="true">
        <price>404</price>
        <currencyId>RUB</currencyId>
        <categoryId>787</categoryId>
    </offer>';

$result = preg_replace_callback(
    '/<price>(.*?)<\/price>/m',
    function ($matches) {
        return $matches[1] * 0.8;
    },
    $str
);


echo "The result of the substitution is " . $result;