//Wine包含Pair模板和sting成员
#include<iostream>
#include <valarray>
#include<string>
 using namespace std;


template<class T1, class T2>
class Pair
{
private:
    T1 a;
    T2 b;
public:
    T1 & first();
    T2 & second();
    T1 first() const { return a; }
    T2 second() const { return b; }
    Pair(const T1 & aval, const T2 & bval) : a(aval), b(bval) { }
    Pair() {}
};

template<class T1,class T2>
T1 & Pair<T1,T2>::first()
{
    return a;
}

template<class T1,class T2>
T2 & Pair<T1,T2>::second()
{
    return b;
}

class Wine
{
private:
    typedef valarray<int> ArrayInt;//valarray<int> 的用法到底是怎么样的？
    typedef Pair<ArrayInt, ArrayInt> PairArray;
    string label;      
    int years;              
    PairArray data;
   
public:
    Wine() : label("none"), years(0), data(ArrayInt(),ArrayInt()) {}//这里的date为什么要 data(ArrayInt(),ArrayInt(）这样初始化，实在不懂？
    Wine(const char * l, int y, const int yr[], const int bot[]);
    Wine(const char * l, const ArrayInt & yr, const ArrayInt & bot);
    Wine(const char * l, const PairArray & yr_bot);
    Wine(const char * l, int y);
    void GetBottles();
    void Show() const;
    const string & Label() { return label; }
    int sum() const { return data.second().sum(); }
};


Wine::Wine(const char * l, int y, const int yr[], const int bot[])
  : label(l), years(y), data(ArrayInt(yr,y),ArrayInt(bot,y) )//data(ArrayInt(yr,y),ArrayInt(bot,y)   这代表什么？
{
}

Wine::Wine(const char * l, const ArrayInt & yr, const ArrayInt & bot)
  : label(l), years(yr.size()), data(ArrayInt(yr), ArrayInt(yr))//data(ArrayInt(yr), ArrayInt(yr)） 这里yr就一个参数代表什么？
{
    if (yr.size() != bot.size())
    {
        cerr << "Year data, bottle data mismatch, array set to 0 size.\n";
        years = 0;
        data = PairArray(ArrayInt(),ArrayInt());
    }
    else
    {
        data.first() = yr;
        data.second() = bot;
    }
}

Wine::Wine(const char * l, const PairArray & yr_bot)
: label(l), years(yr_bot.first().size()), data(yr_bot)  { }

Wine::Wine(const char * l, int y) : label(l), years(y),
    data(ArrayInt(0,y),ArrayInt(0,y))
{}

void Wine::GetBottles()
{
    if (years < 1)
    {
        cout << "No space allocated for data\n";
        return;
    }

    cout << "Enter " << label <<
            " data for " << years << " year(s):\n";
    for (int i = 0; i < years; i++)
    {
        cout << "Enter year: ";
        cin >> data.first()[i];
        cout << "Enter bottles for that year: ";
        cin >> data.second()[i];
    }
}

void Wine::Show() const
{
    cout << "Wine: " << label << endl;
    cout << "\tYear\tBottles\n";
    for (int i = 0; i < years; i++)
        cout << '\t' << data.first()[i]
             << '\t' << data.second()[i] << endl;
}
//----------wine.cpp------
int main()
{
    cout << "Enter name of wine: ";
    char lab[50];
    cin.getline(lab, 50);
    cout << "Enter number of years: ";
    int yrs;
    cin >> yrs;

    Wine holding(lab, yrs);
    holding.GetBottles();   
    holding.Show();         
    const int YRS = 3;
    int y[YRS] = {1993, 1995, 1998};
    int b[YRS] = { 48, 60, 72};
    Wine more("Gushing Grape Red",YRS, y, b);
    more.Show();
    cout << "Total bottles for " << more.Label()
         << ": " << more.sum() << endl;         
    cout << "Bye\n";
    return 0;
}
data的初始化传值为什么是我上面所述实在不明白,大家帮我讲解下吧，谢谢你们啊~