PHP:如何从(多字节)字符串中提取所有预定义的子串？

function extractSubstrings($string, $substring) {
    $substrings = array();
    $position = 0;
    $length = mb_strlen($substring);
    
    while (($pos = mb_strpos($string, $substring, $position)) !== false) {
        $substrings[] = mb_substr($string, $pos, $length);
        $position = $pos + $length;
    }
    
    return $substrings;
}

// 示例用法
$string = "Hello, PHP is a popular programming language. PHP is widely used for web development.";
$substring = "PHP";

$result = extractSubstrings($string, $substring);
print_r($result);

Array
(
    [0] => PHP
    [1] => PHP
)