RegExp emailRexExp = RegExp(r'^[\w-\.]+@([\w-]+.)+[\w-]{2,4}$');

RegExp passwordRexExp = RegExp(r'^(?=.*?[A-Z])(?=.*?[0-9]).{8,}$');

RegExp specialCharRexExp =
    RegExp(r'^(?=.*?[!@#$&*~`)\%\-(_+=;:,.<>/?"[{\]}\|^])');