2012年 上半年 第九周 C++程序设计 （三十）

#include <iostream>  
  
using namespace std;  
  
char x;  
int n;  
  
class CEquation  
{  
private:  
    double a;  
    double b;  
    char unknow;  
public:  
    CEquation(double aa = 0, double bb = 0);  
    friend istream & operator >> (istream &in, CEquation &e);  
    friend ostream & operator << (ostream &out, CEquation &e);  
    double Solve();  
    char getUnknown();  
};  
  
int main()  
{  
    CEquation e;  
    cout << "请输入一元一次方程(输入格式: 3x-8=0): ";  
    cin >> e;  
    cout << "方程为: " << e;  
    cout << "方程的解为: " << e.getUnknown() << "=" << e.Solve() << endl;  
    system("pause");  
    return 0;  
}  
CEquation::CEquation(double aa, double bb)  
{  
    a = aa;  
    b = bb;  
}   
  
istream & operator >> (istream &in, CEquation &e)  
{  
    in >> e.a >> e.unknow >>  e.b >> x >> n;  
    return in;  
}  
ostream & operator << (ostream &out, CEquation &e)  
{  
    if(e.b > 0)  
    {  
        out << e.a << e.unknow << "+" << e.b << x << n;  
        out << endl;  
    }  
    else  
    {  
        out << e.a << e.unknow << e.b << x << n;  
        out << endl;  
    }  
  
    return out;  
}  
double CEquation::Solve()  
{  
    double Solve;  
    Solve = - b / a;  
    return Solve;  
}  
char CEquation::getUnknown()  
{  
    return unknow;  
}