第5周项目1-(4)


Copyright (c) 2016,

All rights reserced.

文件名称：main.cpp

作者：李鑫
完成日期：2016.4.6
问题描述：使用有默认参数的构造函数，不给定实参时，默认边长为1；注意——只需要一个构造函数即可。

#include<iostream>
#include<Cmath>
using namespace std;
class Triangle
{
public:
Triangle(double x=1, double y=1, double z=1);
double perimeter();
double area();
void showMessage();
private:
double a,b,c;
};

Triangle::Triangle(double x, double y, double z)
{
a=x;
b=y;
c=z;
}

double Triangle::perimeter()
{
return (a + b + c);
}

double Triangle::area()
{
double s = (a + b + c) / 2;
return sqrt(s * (s - a) * (s - b) * (s - c));
}

void Triangle::showMessage()
{
cout<<"三角形的三边长分别为："<<a<<' '<<b<<' '<<c<<endl;
cout<<"该三角形的周长为"<<perimeter()<<"，面积为"<<area()<<endl<<endl;
}

int main()
{
Triangle Tri1;
Tri1.showMessage();
Triangle Tri2(1.5);
Tri2.showMessage();
Triangle Tri3(1.5,1.5);
Tri3.showMessage();
Triangle Tri4(7,8,9);
Tri4.showMessage();
return 0;
}