第九周实验报告5

#include "iostream"   using namespace std;  class CEquation  {  private:      double a;     // 未知数系数       double b;     // 常数项       char unknown; // 未知数的符号   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();  };    CEquation::CEquation(double aa,double bb):a(aa),b(bb){}    // 输入方程   istream &operator >> (istream &in,CEquation &e)  {      char ch1,ch2,ch3,ch4;      while(1)      {          cin>>e.a>>ch1>>ch2>>e.b>>ch3>>ch4;          if (ch1>='a' && ch1<='z')              if ((ch2=='+' || ch2=='-') && ch3=='=' && ch4=='0') break;          cout<<"输入的方程格式不符合规范，请重新输入\n";      }      if (ch2=='-') e.b=-e.b;      e.unknown=ch1;      return in;  }    // 输出方程   ostream &operator << (ostream &out,CEquation &e)  {      cout<<e.a<<e.unknown;      if (e.b>=0) cout<<"+";      cout<<e.b<<"=0"<<endl;      return out;  }    // 求解   double CEquation::Solve()  {      double x;      if (a==0)      {          if (b==0) cout<<"任意一个实数均为方程的解。"<<endl;          else cout<<"方程无解。"<<endl;          return 0;      }      x=-b/a;      return x;  }    char CEquation::getUnknown()  {      return unknown;  }    int main()  {      CEquation e;      cout<<"请输入一元一次方程(输入格式：3x-8=0)：";      cin>>e;   //在两次测试中，分别输入3x-8=0和5s+18=0       cout<<"方程为："<<e;      cout<<"方程的解为："<<e.getUnknown()<<"="<<e.Solve()<<endl; //对两次测试，分别输出x=...和s=...       e.Solve();      system("pause");      return 0;  }