#include <iostream> using namespace std; class CEquation { private: double a;//未知数系数 double b;//常数项 char unknow;//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();//返回解方程的结果 char getUnknow();//返回未知数用什么符号 }; int main() { CEquation e; cout<<"请输入一元一次方程(输入格式:3x-8=0):"; cin>>e;//两次测试中,分别输入3x-8=0和5s+18=0 cout<<"方程的解为:"<<e.getUnknow()<<"="<<e.Solve()<<endl;//对两次测试,分别输出x=。。。和s=。。。 return 0; } istream &operator >>(istream &in,CEquation &e) { char d;//= int f;//0 while(1) { in>>e.a>>e.unknow>>e.b>>d>>f; if(d=='='&&f==0) {break;} else {cout<<"输入格式错误,请重新输入:"<<endl;}} return in; } CEquation::CEquation(double aa,double bb){ a=aa; b=bb; } char CEquation::getUnknow() { return unknow; } double CEquation::Solve()//返回解方程的结果 { double c; c=(0-b)/a; return c; }