类模板

1、类模板使用举例

#include <iostream>
using namespace std;

/* 定义类模板 */
template <class T1,  class T2 = int>  // 默认模板参数类型设置为int
class MyTemplate
{
private:    
    T1 t1;
    T2 t2;

public:
/* 构造函数 */
    MyTemplate(T1 x, T2 y)
    {
        t1 = x;
        t2 = y;
    }

/*成员函数*/
    void display()
    {
        cout << "t1="<<t1 << "   " << "t2="<< t2<< endl;
    }
};

int main(int argc,  char *argv[])
{
    int a = 123;
    double b = 10.12;
    MyTemplate<int, double> mt1(a, b);   //通过MyTemplate<int, double>定义对象mt, 传递参数a和b
    MyTemplate<int> mt2(a,b);  // 第二个参数采用默认参数类型int
    mt1.display();   
    mt2.display();
}

xuanmiao@linux:~/Test/C++$ ./test
t1=123   t2=10.12
t1=123   t2=10

 

2、参数默认值

#include <iostream>
using namespace std;

template <typename T1,  typename T2,  int defaultNum = 10>
class MyTemplate
{
private:
    T1 t1;
    T2 t2;

public:
    MyTemplate(T1 x, T2 y)
    {
        t1 = x + defaultNum;
        t2 = y + defaultNum;
    }

    void display()
    {
        cout <<"t1="<<t1<<"               "<<"t2="<<t2<<endl;
    }
};

int main(int argc, char *argv[])
{
    int a = 10;
    double b = 3.15;
    MyTemplate<int , double>  mt(a,b); //defaultNum采取默认参数10
    MyTemplate<int , double, 100>  mt2(a,b); //defaultNum采取设置参数100
    mt.display();
    mt2.display();
}

xuanmiao@linux:~/Test/C++$ ./test
t1=20               t2=13.15
t1=110               t2=103.15

 

 

3、通用模板类的使用

#include <iostream>
 using namespace std;

 /* 普通类 */
 class Date
{
    int iMonth, iDay, iYear;
    char Format[128];

public:
    Date(int m=0, int d=0, int y=0)
    {
        iMonth = m;
        iDay = d;
        iYear = y;
    }

    void display()
    {
        cout << "Month=" << iMonth<<" ";
        cout << "Day=" << iDay<<" ";
        cout << "Year=" << iYear<<" ";
        cout << endl;
    }

    friend ostream& operator << (ostream& os, const Date t)
    {
        cout << "Month=" << t.iMonth << " ";
        cout << "Day=" << t.iDay << " ";
        cout << "Year=" << t.iYear <<  " ";
        cout << endl;
        return os;
    }
};

/* 通用模板类 */
template <class T>
class Set
{
    T t;
public:
    Set(T st) : t(st)
    {
    }

    void Display()
    {
        cout << t << endl;
    }
};

int main(int argc, char * argv[ ])
{
    cout << endl << "通过普通类Date定义对象date,通过display函数展示:"<< endl;
    Date date(5,6,2025);    // 创建Date类对象date
    date.display();   

    cout << endl << "通过通用模板类Set<Date>定义对象sdate:" << endl;
    Set<Date> sdate = date;    // 将Date类对象赋值给Set<Date>类对象sdate
    sdate.Display();

    return 0;
}

xuanmiao@linux:~/Test/C++$ ./test

通过普通类Date定义对象date,通过display函数展示:
Month=5 Day=6 Year=2025 

通过通用模板类Set<Date>定义对象sdate,通过友元运算符展示：
Month=5 Day=6 Year=2025 

 

4、定制模板类成员函数

#include <iostream>
 using namespace std;

 /* 普通类 */
 class Date
{
    int iMonth, iDay, iYear;
    char Format[128];

public:
    Date(int m=0, int d=0, int y=0)
    {
        iMonth = m;
        iDay = d;
        iYear = y;
    }

    void display()
    {
        cout << "Month=" << iMonth<<" ";
        cout << "Day=" << iDay<<" ";
        cout << "Year=" << iYear<<" ";
        cout << endl;
    }

    friend ostream& operator << (ostream& os, const Date t)
    {
        cout << "Month=" << t.iMonth << " ";
        cout << "Day=" << t.iDay << " ";
        cout << "Year=" << t.iYear <<  " ";
        cout << endl;
        return os;
    }
};

 /* 通用模板类 */
template <typename Type>
class Set
{
    Type t;

public:
    Set(Type input) : t(input) {};
    void templateDisplay(); 
};

/* 定义Date类的Display函数 */
template<>
void Set<Date>::templateDisplay()
{
    cout <<"Date:"<< t << endl;
}

/* 主程序 */
int main(int argc, char * argv[ ])
{
    cout << endl << "通过普通类Date定义对象date,通过display函数展示:"<< endl;
    Date date(5,6,2025);    // 创建Date类对象date
    date.display();   

    cout << endl << "通过通用模板类Set<Date>定义对象sdate,通过templateDisplay函数展示:" << endl;
    Set<Date> sdate = date;    // 将Date类对象赋值给Set<Date>类对象sdate
    sdate.templateDisplay();

    return 0;
}

xuanmiao@linux:~/Test/C++$ ./test

通过普通类Date定义对象date,通过display函数展示:
Month=5 Day=6 Year=2025 

通过通用模板类Set<Date>定义对象sdate,通过templateDisplay函数展示:
Date:Month=5 Day=6 Year=2025