#include <iostream>

//base class validation
struct validation
{
validation(){}
~validation(){ delete is_val; }
//pure virtual function to enforce reimplementation
virtual void menu() = 0;
virtual bool isValid() = 0;

protected:
std::string str;
validation* is_val;
};

//function foward declaration
void menu_All();

int main()
{
menu_All();
return 0;
}

struct gmail: validation
{
gmail(){}

gmail(std::string mail): _mail(mail){}

~gmail()
{
delete is_val;
_mail.clear();
}

bool isValid()
{
std::string server("@gmail.com");

std::string piece(_mail.substr(_mail.size()-server.size()));

return !piece.compare(server);
}

void menu()
{
do{
std::cout<<"\n\tEnter your google e-mail: ";
std::cin>>str;

is_val = new gmail(str);

if(is_val->isValid())
std::cout<<"\n\tEmail: " << str << " is Valid.\n\n";
else
std::cout<<"\n\tEmail: " << str << " is Invalid.\n\n";

}while(!is_val->isValid());
}

private:
std::string _mail;
};

struct uol: validation
{
uol(){}

uol(std::string mail): _mail(mail){}

~uol()
{
delete is_val;
_mail.clear();
}

bool isValid()
{
std::string server("@uol.com.br");

std::string piece(_mail.substr(_mail.size()-server.size()));

return !piece.compare(server);
}

void menu()
{
do{
std::cout<<"\n\tEnter your uol e-mail: ";
std::cin>>str;

is_val = new uol(str);

if(is_val->isValid())
std::cout<<"\n\tEmail: " << str << " is Valid.\n\n";
else
std::cout<<"\n\tEmail: " << str << " is Invalid.\n\n";

}while(!is_val->isValid());
}

private:
std::string _mail;
};

struct bol: validation
{
bol(){}

bol(std::string mail): _mail(mail){}

~bol()
{
delete is_val;
_mail.clear();
}

bool isValid()
{
std::string server("@bol.com.br");

std::string piece(_mail.substr(_mail.size()-server.size()));

return !piece.compare(server);
}

void menu()
{
do{
std::cout<<"\n\tEnter your bol e-mail: ";
std::cin>>str;

is_val = new bol(str);

if(is_val->isValid())
std::cout<<"\n\tEmail: " << str << " is Valid.\n\n";
else
std::cout<<"\n\tEmail: " << str << " is Invalid.\n\n";

}while(!is_val->isValid());
}

private:
std::string _mail;
};

void menu_All()
{
int op;
validation* m_val;

enum { Gmail=1, Uol, Bol, Exit };

do{
std::cout << "\n\tValidation e-mail"
"\n\t[1]-Gmail"
"\n\t[2]-Uol"
"\n\t[3]-Bol"
"\n\t[4]-Exit"
"\n\tEnter: ";
std::cin>>op;

switch(op)
{
case Gmail:

m_val = new gmail();

m_val->menu();

break;

case Uol:

m_val = new uol();

m_val->menu();

break;

case Bol:

m_val = new bol();

m_val->menu();

break;

case Exit:

std::cout << "\n\tGood Bye!\n\n";
exit(1);

break;

default:

std::cout << "\n\tInvalid Option!\n\n";

break;
}
}while(1);
}