Ej6C++

#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

struct date
{
    unsigned int day;
    unsigned int month;
    unsigned int year;

    bool month_day_match (const date& d1)const
    {
        return ((d1.month == month) && (d1.day == day));
    };
};

struct friend_pair
{
    date birthdate;
    string name;

    void print_friend_pair ()
    {
        cout << name << ": " << birthdate.day << "/" << birthdate.month << "/" << birthdate.year << endl;
    };
    bool operator < (const friend_pair & second)const   /* We overload the < operator for later use */
    {                           /* Orders two dates without paying attention to the year */

        bool result;

        if (birthdate.month < second.birthdate.month)
        {
            result = true;
        } else if (birthdate.month > second.birthdate.month) {
            result = false;
        } else if (birthdate.day <= second.birthdate.day) {
            result = true;
        } else {
            result = false;
        }
        return result;
    };
};

class FriendsGroup
{
    private:
    vector<friend_pair> friend_list;

    public:
    void add_friend (date birthdate, string friend_name)
    {
        friend_pair new_friend;
        new_friend.birthdate = birthdate;
        new_friend.name = friend_name;

        friend_list.push_back (new_friend);
    };
    void get_new_friend ()
    {
        string friend_name;
        date birthdate;

        cout << "Enter the Name \n";
        cin >> friend_name;

        cout << "Enter the Date, separated by spaces (dd mm yyyy) \n";
        cin >> birthdate.day >> birthdate.month >> birthdate.year;

        while (birthdate.day > 31 || birthdate.month > 12)
        {
            cout << "Please input the date again, separated by spaces (dd mm yyyy) \n";
            cin >> birthdate.day >> birthdate.month >> birthdate.year;
        }
        add_friend (birthdate, friend_name);
    };
    void show ()
    {
        int i;
        int printing;
        friend_pair current;
        friend_pair next;

        if (friend_list.size() == 0)            /* If there are no friends to show, do nothing */
        {
            return;
        }

        std::sort (friend_list.begin(), friend_list.end() );

        printing = 0;
        current = friend_list[0];
        for (i=1; i<friend_list.size(); i++)
        {
            next = friend_list[i];
            if (current.birthdate.month_day_match(next.birthdate) )
            {
                current.print_friend_pair ();
                printing = 1;
                current = next;
            } else {
                if (printing == 1)
                {
                    current.print_friend_pair ();
                    current = next;
                    printing = 0;
                } else {
                    current = next;
                }
            }
        }
        if (printing == 1)
        {
            current.print_friend_pair ();
        }
    };
    FriendsGroup()
    {
        friend_list.resize (0);
    };
};

int main (void)
{
    FriendsGroup people;
    string status;
    string input;

    status = "Receiving";

    while (status == "Receiving")
    {
        cout << "Choose your action: Add, Show, Exit \n";
        cin >> input;

        if (input == "Exit")
        {
            status = "Exit";
        } else if (input == "Show") {
            people.show();
        } else if (input == "Add") {
            people.get_new_friend ();
        } else {
            cout << "That is not a valid input \n";
        }
    }

    return 0;
}