PHP 手机号中间4位加密

        很实用，可以用在其他字符串加密。

    /**
     * 中间加密 字符串截取法
     */
    public static function encryptTel($tel) {
        $new_tel = substr($tel, 0, 3).'****'.substr($tel, 7);        return $new_tel;
    }    /**
     * 中间加密 替换字符串的子串
     */
    public static function encryptTel($tel) {
        $new_tel = substr_replace($tel, '****', 3, 4);        return $new_tel;
    }    /**
     * 中间加密 用正则
     */
    public static function encryptTel($tel) {
        $new_tel = preg_replace('/(d{3})d{4}(d{4})/', '****', $tel);        return $new_tel;
    }
    /**
     * 中间加密 字符串截取法
     */
    public static function encryptTel($tel) {
        $new_tel = substr($tel, 0, 3).'****'.substr($tel, 7);        return $new_tel;
    }    /**
     * 中间加密 替换字符串的子串
     */
    public static function encryptTel($tel) {
        $new_tel = substr_replace($tel, '****', 3, 4);        return $new_tel;
    }    /**
     * 中间加密 用正则
     */
    public static function encryptTel($tel) {
        $new_tel = preg_replace('/(d{3})d{4}(d{4})/', '****', $tel);        return $new_tel;
    }
    /**
     * 中间加密 字符串截取法
     */
    public static function encryptTel($tel) {
        $new_tel = substr($tel, 0, 3).'****'.substr($tel, 7);        return $new_tel;
    }    /**
     * 中间加密 替换字符串的子串
     */
    public static function encryptTel($tel) {
        $new_tel = substr_replace($tel, '****', 3, 4);        return $new_tel;
    }    /**
     * 中间加密 用正则
     */
    public static function encryptTel($tel) {
        $new_tel = preg_replace('/(d{3})d{4}(d{4})/', '****', $tel);        return $new_tel;
    }