第十周上机项目5方程也是类

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/* *Copyright (c) 2015, 烟台大学计算机学院 *All rights reserved. *文件名称：text.cpp *作者：陈栋梁 *完成日期：2015年 5月 13日 *版本号：v1.0 * */#include "iostream"using namespace std;class CEquation{private:    double a;    double b;    char unknown;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) {}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;}ostream &operator << (ostream &out,CEquation &e){    cout<<e.a<<e.unknown;    if (e.b>=0) cout<<"+";    cout<<e.b<<"=0"<<endl;    return out;}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<<"请输入方程(格式：ax-b=0，a、b为常数，x处是代表未知数的字母)：";    cin>>e;    cout<<"方程为："<<e;    cout<<"方程的解为："<<e.getUnknown()<<"="<<e.Solve()<<endl;    e.Solve();}
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