【C++ Primer Plus习题】14.1
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问题:
解答:
main.cpp
#include <iostream>
#include "wine.h"
using namespace std;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!" << endl;return 0;
}wine.h
#include <iostream>
#include <string>
#include <valarray>using namespace std;template <class T1, class T2> class Pair;
typedef valarray<int> ArrayInt;
typedef Pair<ArrayInt, ArrayInt> PairArray;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() {}
};class Wine
{
private:string label;PairArray info;int year;
public:Wine(const char* l, int y, const int yr[], const int bot[]);Wine(const char* l, int y);void GetBottles();const string& Label()const;int sum()const;void show();
};wine.cpp
#include "wine.h"template<class T1, class T2>
T1& Pair<T1, T2>::first()
{return a;
}template<class T1, class T2>
T2& Pair<T1, T2>::second()
{return b;
}Wine::Wine(const char* l, int y, const int yr[], const int bot[]):info(ArrayInt(yr,y),ArrayInt(bot,y))
{this->label = l;this->year = y;
}
Wine::Wine(const char* l, int y):info(ArrayInt(0,0),ArrayInt(0,0))
{this->label = l;this->year = y;
}
void Wine::GetBottles()
{cout << "Enter " << label << " data for" << year << "year:" << endl;info.first().resize(year);info.second().resize(year);for (int i = 0; i < year; i++){cout << "Enter year: ";cin >> info.first()[i];cout << "Enter bottles for that year: ";cin >> info.second()[i];}
}
const string& Wine::Label()const
{return label;
}
int Wine::sum()const
{return info.second().sum();
}
void Wine::show()
{cout << "Wine: " << label << endl;cout << " Year Bottles" << endl;for (int i = 0; i < year; i++){cout << " " << info.first()[i] << " " << info.second()[i] << endl;}
}
运行结果:
考查点:
- 模版类
- 类型重定义typedef
- 组合
- valarray模版类
注意:
- 构造函数用的初始化列表进行初始化,且用了valarray构造函数
- valarray可重新指定数组大小
- valarray也可以计算数组总数
- 模版类一定要记得说明哦
2024年9月9日19:49:55