C++类模板再学习

之前已经学习了C++类模板；类模板的写法和一般类的写法有很大的差别；不容易熟悉；下面再做一遍；

做一个椭圆类，成员有长轴长度和短轴长度；

// ellipse.h: interface for the ellipse class.
//
//#if !defined(AFX_ELLIPSE_H__51CD537E_D0B0_40F9_AD63_92F0502C0430__INCLUDED_)
#define AFX_ELLIPSE_H__51CD537E_D0B0_40F9_AD63_92F0502C0430__INCLUDED_#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000template<class T1, class T2>class ellipse  
{
public:ellipse(T1 a, T2 b) : older(a), lack(b){ }public:T1 getolder() const;void setolder(T1 a);T2 getlack() const;void setlack(T2 b);private:T1 older;  //长轴长度T2 lack;  //短轴长度
};template<class T1, class T2>
T1 ellipse<T1, T2>::getolder() const {return older;
}template<class T1, class T2>
void ellipse<T1, T2>::setolder(T1 a){older = a;
}template<class T1, class T2>
T2 ellipse<T1, T2>::getlack() const{return lack;
}template<class T1, class T2>
void ellipse<T1, T2>::setlack(T2 b){lack = b;
}#endif // !defined(AFX_ELLIPSE_H__51CD537E_D0B0_40F9_AD63_92F0502C0430__INCLUDED_)

类名之前先写，
template<class T1, class T2>
T1和T2是两个成员的类型；

ellipse(T1 a, T2 b) : older(a), lack(b){ }
构造函数，接收2个参数，一个类型为T1，一个类型为T2；把a传给成员变量older，把b传给成员变量lack；

T1 older; //长轴长度
T2 lack; //短轴长度
成员变量的定义，类型写为T1、T2，T1、T2可以替换为C++的各种数据类型；

template<class T1, class T2>
每个成员函数体之前也写上这个；

调用如下；

void CTyView::OnDraw(CDC* pDC)
{CTyDoc* pDoc = GetDocument();ASSERT_VALID(pDoc);// TODO: add draw code for native data hereCString str1;ellipse<int, int> e1(100, 20);str1.Format("长轴：%d，短轴：%d", e1.getolder(), e1.getlack());pDC->TextOut(50, 50, str1);ellipse<char*, char*> e2("20cm", "10cm");str1.Format("长轴：%s，短轴：%s", e2.getolder(), e2.getlack());pDC->TextOut(50, 80, str1);ellipse<double, double> e3(155.5, 97.5);str1.Format("长轴：%f，短轴：%f", e3.getolder(), e3.getlack());pDC->TextOut(50, 140, str1);
}

运行；