EX 7

总结：这次实验算是自闭场吧，发现了有好多不会的知识点，大概是上次作业搞得没听讲的缘故吧。

Problem A: 数组类（II）

main 函数：

int main()
{
    int cases, len;
    cin >> cases;
    for(int ca = 1; ca <= cases; ca++)
    {
        cin >> len;
        if(ca % 3 == 0)
        {
            Array<char> chr_arr(len);
            for(int i = 0; i < chr_arr.size(); i++)
                cin >> chr_arr[i];
            chr_arr.put(10);
        }
        if(ca % 3 == 1)
        {
            Array<int> int_arr(len);
            for(int i = 0; i < int_arr.size(); i++)
                cin >> int_arr[i];
            int_arr.put(10);
        }
        if(ca % 3 == 2)
        {
            Array<double> dbl_arr(len);
            for(int i = 0; i < dbl_arr.size(); i++)
                cin >> dbl_arr[i];
            dbl_arr.put(10);
        }
    }
}

　遗漏知识点：sort从大到小排，加上第三个参数great<type>()；

AC代码：

#include <bits/stdc++.h>
using namespace std;
template <class T>
class Array
{
    T *p;
    int len;
public:
    Array(int l = 0){p = new T[l+1];len = l;}
    int size(){return len; }
    void put(int n)
    {
        if(n==0)
            return ;
        sort(p,p+len,greater<int>());
        int en = len<n?len:n;
        cout << p[0];
        for(int i = 1;i<en;i++)
            cout << " " << p[i] ;
        cout << endl;
    }
    T& operator[](int n)//因为要更改输出中的值，所以要传引用。
    {
        return p[n];
    }
    ~Array()//原则上来说，要判断p是否为空指针，但，根据main函数编程嘛，嘿嘿
    {
        len = 0;
        delete []p;
    }
};
int main()
{
    int cases, len;
    cin >> cases;
    for(int ca = 1; ca <= cases; ca++)
    {
        cin >> len;
        if(ca % 3 == 0)
        {
            Array<char> chr_arr(len);
            for(int i = 0; i < chr_arr.size(); i++)
                cin >> chr_arr[i];
            chr_arr.put(10);
        }
        if(ca % 3 == 1)
        {
            Array<int> int_arr(len);
            for(int i = 0; i < int_arr.size(); i++)
                cin >> int_arr[i];
            int_arr.put(10);
        }
        if(ca % 3 == 2)
        {
            Array<double> dbl_arr(len);
            for(int i = 0; i < dbl_arr.size(); i++)
                cin >> dbl_arr[i];
            dbl_arr.put(10);
        }
    }
}

　　

Problem B: 数量的类模板

main 函数：

int main()
{
    Data<int> iData[1001];
    Data<double> dData[1001];
    int cases, num;
    char ch;
    int u;
    double v;
    Data<int> a(10), b(20);
    Data<double> c(3.14), d(-4.1);
    cout<<"a + b = "<<(a + b)<<endl;
    cout<<"max(a, b) = "<<(a > b ? a : b)<<endl;
    cout<<"min(a, b) = "<<(a < b ? a : b)<<endl;
    cout<<"c + d = "<<(c + d)<<endl;
    cout<<"max(c, d) = "<<(c > d ? c : d)<<endl;
    cout<<"min(c, d) = "<<(c < d ? c : d)<<endl;
    cin>>cases;
    for (int i = 0; i < cases; i++)
    {
        cin>>ch;
        cin>>num;
        for (int j = 0; j < num; j++)
        {
            if (ch == 'i')
            {
                cin>>u;
                iData[j].setValue(u);
            }
            else if (ch == 'd')
            {
                cin>>v;
                dData[j].setValue(v);
            }
        }
        if (ch == 'i')
        {
            cout<<GetResult<int>::getMax(iData, num);
            cout<<" "<<GetResult<int>::getMin(iData, num);
            cout<<" "<<GetResult<int>::getSum(iData, num)<<endl;
        }
        else if (ch == 'd')
        {
            cout<<GetResult<double>::getMax(dData, num);
            cout<<" "<<GetResult<double>::getMin(dData, num);
            cout<<" "<<GetResult<double>::getSum(dData, num)<<endl;
        }
    }
    return 0;
}

AC代码：

#include <bits/stdc++.h>
using namespace std;
template <class T>
class Data
{
    //template <class T1>
    //friend class GetResult;
    T value;
public:
    Data(int l ):value(l) {};
    Data(double l):value(l) {};
    Data():value(0) {};
    bool operator>(Data<T> &b)
    {
        return value>b.value;
    }
    bool operator<(Data<T> &b)
    {
        return value < b.value;
    }
    Data<T> operator +(Data<T> &b)
    {
        return Data<T>(value+b.get());
    }
    template <class T2>//着重点，如何在类模板中用友元重载输出运算符
    friend ostream&operator<<(ostream &os, const Data<T2> &b);
    void setValue(T a)
    {
        value =a;
    }
    T get()
    {
        return value;
    }
};
template <class T>
ostream&operator<<(ostream &os, const Data<T> &b)
{
    os << fixed << setprecision(2) << b.value;
    return os;
}
template <class T>
class GetResult
{
    //friend class Data;
public:
    static Data<T> getSum(Data<T> *arr, int num)
    {
        Data<T> b;
        for(int i = 0; i<num; i++)
            b.setValue(b.get()+arr[i].get());
        return b;
    }
    static Data<T> getMax(Data<T> *arr, int num)
    {
        Data<T> b(arr[0].get());
        for(int i = 1; i<num; i++)
            b.setValue(arr[i].get()>b.get()?arr[i].get():b.get());
        return b;
    }
    static Data<T> getMin(Data<T> *arr, int num)
    {
        Data<T> b(arr[0].get());
        for(int i = 1; i<num; i++)
            b.setValue(arr[i].get()<b.get()?arr[i].get():b.get());
        return b;
    }
};
int main()
{
    Data<int> iData[1001];
    Data<double> dData[1001];
    int cases, num;
    char ch;
    int u;
    double v;
    Data<int> a(10), b(20);
    Data<double> c(3.14), d(-4.1);
    cout<<"a + b = "<<(a + b)<<endl;
    cout<<"max(a, b) = "<<(a > b ? a : b)<<endl;
    cout<<"min(a, b) = "<<(a < b ? a : b)<<endl;
    cout<<"c + d = "<<(c + d)<<endl;
    cout<<"max(c, d) = "<<(c > d ? c : d)<<endl;
    cout<<"min(c, d) = "<<(c < d ? c : d)<<endl;
    cin>>cases;
    for (int i = 0; i < cases; i++)
    {
        cin>>ch;
        cin>>num;
        for (int j = 0; j < num; j++)
        {
            if (ch == 'i')
            {
                cin>>u;
                iData[j].setValue(u);
            }
            else if (ch == 'd')
            {
                cin>>v;
                dData[j].setValue(v);
            }
        }
        if (ch == 'i')
        {
            cout<<GetResult<int>::getMax(iData, num);
            cout<<" "<<GetResult<int>::getMin(iData, num);
            cout<<" "<<GetResult<int>::getSum(iData, num)<<endl;
        }
        else if (ch == 'd')
        {
            cout<<GetResult<double>::getMax(dData, num);
            cout<<" "<<GetResult<double>::getMin(dData, num);
            cout<<" "<<GetResult<double>::getSum(dData, num)<<endl;
        }
    }
    return 0;
}

模板类中友元的使用(模板类之间并非无法实现友元)：

https://blog.csdn.net/hqz1989/article/details/21942867

Problem C: 模板是个好东西

main 函数：

int main()
{
    string n;
    int x, y, d;
    char c;
    cin>>n;
    cin>>x>>y>>d;
    cin>>c;
    Point p(x, y);
    Data<char> aChar(c);
    Data<int> anInt(d);
    Data<Point> aPoint(p);
    Data<string> aString(n);
    aChar.show();
    anInt.show();
    aString.show();
    aPoint.show();
    return 0;
}

水题，怎么说怎么写就行：

#include <bits/stdc++.h>
using namespace std;
class Point
{
    int x,y;
public:
    Point():x(0),y(0){};
    Point(int _x,int _y):x(_x),y(_y){};
    friend ostream&operator<< (ostream &os,const Point&b)
    {
        os << b.x << " " << b.y  ;
        return os;
    }
};
template <class T>
class Data
{
    T value;
public:
    Data(T b):value(b){};
    void show()
    {
        cout  << value << endl;
    }
};
int main()
{
    string n;
    int x, y, d;
    char c;
    cin>>n;
    cin>>x>>y>>d;
    cin>>c;
    Point p(x, y);
    Data<char> aChar(c);
    Data<int> anInt(d);
    Data<Point> aPoint(p);
    Data<string> aString(n);
    aChar.show();
    anInt.show();
    aString.show();
    aPoint.show();
    return 0;
}