示例：

字符串截取法

public static function encryptTel($tel) {
    $new_tel = substr($tel, 0, 3).'****'.substr($tel, 7);
    return $new_tel;
}

替换字符串:

public static function encryptTel($tel) {
    $new_tel = substr_replace($tel, '****', 3, 4);
    return $new_tel;
}

正则:

public static function encryptTel($tel) {
    $new_tel = preg_replace('/(\d{3})\d{4}(\d{4})/', '$1****$2', $tel);
    return $new_tel;
}

以上便是PHP实现手机号码中间四位数替换成星号*的方法,请大家参考。