php 判断是否含有某中文字符

<?php
function containsChinese($string, $char) {
    // 将目标字符转换为UTF-8编码
    $char = mb_convert_encoding($char, 'UTF-8', 'auto');
    // 获取字符串的长度
    $len = mb_strlen($string, 'UTF-8');
    // 遍历字符串中的每个字符
    for ($i = 0; $i < $len; $i++) {
        // 获取当前位置的字符
        $currentChar = mb_substr($string, $i, 1, 'UTF-8');
        // 比较当前字符是否为目标字符
        if ($currentChar === $char) {
            return true;
        }
    }
    return false;
}

$string = "你好，世界！";
$char = "世";

if (containsChinese($string, $char)) {
    echo "字符串包含中文字符：$char";
} else {
    echo "字符串不包含中文字符：$char";
}
?>

<?php
function containsChineseRegex($string, $char) {
    // 将目标字符转换为UTF-8编码
    $char = preg_quote($char, '/');
    // 使用正则表达式匹配
    return preg_match("/$char/u", $string);
}

$string = "你好，世界！";
$char = "世";

if (containsChineseRegex($string, $char)) {
    echo "字符串包含中文字符：$char";
} else {
    echo "字符串不包含中文字符：$char";
}
?>