目录

1.数据抽象

数据抽象：就是把它当做黑箱子使用，内部实现与外部接口分开
C++类实现数据抽象，如sort()函数，ostream的cout对象

#include <iostream>
using namespace std;class Adder{public:// 构造函数Adder(int i = 0){total = i;}// 对外的接口void addNum(int number){total += number;}// 对外的接口int getTotal(){return total;};private:// 对外隐藏的数据int total;
};
int main( )
{Adder a;a.addNum(10);a.addNum(20);a.addNum(30);cout << "Total " << a.getTotal() <<endl;return 0;
}

当上面的代码被编译和执行时，它会产生下列结果：
Total 60

2.数据封装

#include <iostream>
using namespace std;class Adder{public:// 构造函数Adder(int i = 0){total = i;}// 对外的接口void addNum(int number){total += number;}// 对外的接口int getTotal(){return total;};private:// 对外隐藏的数据int total;
};
int main( )
{Adder a;a.addNum(10);a.addNum(20);a.addNum(30);cout << "Total " << a.getTotal() <<endl;return 0;
}

当上面的代码被编译和执行时，它会产生下列结果：
Total 60

3.抽象接口类

#include <iostream>using namespace std;// 基类
class Shape 
{
public:// 提供接口框架的纯虚函数virtual int getArea() = 0;void setWidth(int w){width = w;}void setHeight(int h){height = h;}
protected:int width;int height;
};// 派生类
class Rectangle: public Shape
{
public:int getArea(){ return (width * height); }
};
class Triangle: public Shape
{
public:int getArea(){ return (width * height)/2; }
};int main(void)
{Rectangle Rect;Triangle  Tri;Rect.setWidth(5);Rect.setHeight(7);// 输出对象的面积cout << "Total Rectangle area: " << Rect.getArea() << endl;Tri.setWidth(5);Tri.setHeight(7);// 输出对象的面积cout << "Total Triangle area: " << Tri.getArea() << endl; return 0;
}

当上面的代码被编译和执行时，它会产生下列结果：
Total Rectangle area: 35
Total Triangle area: 17