设计一个三角形类Triangle，包含三角形三条边长的私有数据成员，要求使用重载运算符”+”，以实现求两个三角形对象的面积之和。

#include <iostream>
#include<cstring>
#include<math.h>
using namespace std;

class Triangle
{
private:
    double a,b,c,s;
public:
    Triangle();
    Triangle(double a1,double b1,double c1);
    friend double operator + (Triangle &s1,Triangle &s2);
};
Triangle::Triangle(double a1,double b1,double c1)
{
    a=a1;
    b=b1;
    c=c1;
    double p=(double)(a+b+c)/2;
    s=sqrt(p*(p-a)*(p-b)*(p-c));
}
double operator + (Triangle &s1,Triangle &s2)
{

    return s1.s+s2.s;
}
int main()
{
    Triangle s1(3,4,5),s2(3,4,5);
    cout<<s1+s2;
    return 0;
}