设计一个Triangle类

#include<iostream> #include<cmath> using namespace std; class Triangle { public: friend double operator + (const Triangle& t1,const Triangle& t2); Triangle(double t_a,double t_b,double t_c); Triangle(); void area(); void input(); void output(); private: double a; double b; double c; double areas; }; double operator + (const Triangle& t1,const Triangle& t2) { double temp; temp=t1.areas+t2.areas; return temp; } Triangle::Triangle(double t_a,double t_b,double t_c) { a=t_a; b=t_b; c=t_c; } Triangle::Triangle():a(0),b(0),c(0),areas(0) { } void Triangle::area() { double s; s=(a+b+c)/2; areas=sqrt(s*(s-a)*(s-b)*(s-c)); } void Triangle::input() { cin >>a>>b>>c; while(((a+b)<c)||((a+c)<b||((b+c)<a))) { cout<<"输入数据错误,请重新输入!"; cin >>a>>b>>c; } } void Triangle::output() { cout <<areas<< endl; } void main() { Triangle tri1,tri2; double tri; cout<<"请输入第一个三角形的三条边:"; tri1.input(); tri1.area(); cout<<"请输入第二个三角形的三条边:"; tri2.input(); tri2.area(); tri=tri1+tri2; cout << "两个三角形的面积之和为:" <<tri<< endl; }