阅读以下说明和C++程序，将应填入（n)处的字句写在答题纸的对应栏内。说明 以下程序的功能是计算三

阅读以下说明和C++程序，将应填入(n)处的字句写在答题纸的对应栏内。

说明

以下程序的功能是计算三角形、矩形和正方形的面积并输出。

程序由4个类组成：类Triangle、Rectangle和Square分别表示三角形、矩形和正方形；抽象类Figure提供了一个纯虚拟函数getArea()，作为计算上述三种图形面积的通用接口。

c++程序

include ＜iostream.h＞

inclule ＜math.h＞

class Figure {

public:

virtual double getArea()= 0; // 纯虚拟函数

};

class Rectangle: (1) {

protected:

double height;

double width;

public:

Rectangle() { };

Rectangle(double height, double width) {

this-＞height = height;

this-＞width = width;

}

double getArea() {

return (2) ;

}

class Square: (3) {

public:

Square(double width) {

(4) ;

}

};

class Triangle: (5) {

double la;

double lb;

double lc;

public:

Triangle(double la, double lb, double lc) {

this-＞la = la; this-＞lb ='lb; this-＞lc = lc;

}

double getArea() {

double s = (la+lb+lc)/2.0;

return sqrt(s*(s-la)*(s-lb)*(s-lc));

} }; void main() {

Figure* figures[3] = {

new Triangle(2,3,3), new Rectangle(5,8), new Square(5)};

for (int i = 0; i ＜ 3; i++) {

com ＜＜ "figures[" ＜＜ i ＜＜ "] area =" ＜＜ (figures[i])-＞getArea0 ＜＜ endl;

}