/*
*Copyright (c) 2014, 烟台大学计算机学院
*All rights reserved.
*文件名称:week9-5.cpp
*作者:高赞
*完成日期:2015年 5 月 6 日
*版本号:v1.0
*
* 问题描述:设计一元一次方程类,求形如ax+b=0的方程的解。
*/
#include <iostream>
#include <cstdlib>
using namespace std;
class CEquation
{
private:
double a; // 未知数系数
double b; // 常数项
char unknown; // 代表未知数的符号
public:
CEquation(double aa=0,double bb=0):a(aa),b(bb) {}
friend istream &operator >> (istream &in,CEquation &e);
friend ostream &operator << (ostream &out,CEquation &e);
double Solve();
char getUnknown();
};
double CEquation::Solve()
{
if(a==0)
{
cout<<"方程无实根。"<<endl;
exit(0);
}
else return (-b/a);
}
char CEquation::getUnknown()
{
return unknown;
}
istream &operator >> (istream &in,CEquation &e)
{
char char1,char2,char3;
while(1)
{
in>>e.a>>e.unknown>>char1>>e.b>>char2>>char3;
if (e.unknown>='a' && e.unknown<='z')
if((char1=='+'||char1=='-')&&char2=='='&&char3=='0')
break;
cout<<"输入格式错误,重新输入:";
}
if(char1=='-')
e.b=-e.b;
return in;
}
ostream &operator << (ostream &out,CEquation &e)
{
if(e.b<0)
out<<e.a<<e.unknown<<e.b<<"=0"<<endl;
else if(e.b>0)
out<<e.a<<e.unknown<<'+'<<e.b<<"=0"<<endl;
else
{
if(e.a==0)
out<<"0=0"<<endl;
else out<<e.a<<e.unknown<<"=0"<<endl;
}
return out;
}
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; //在两次测试中,分别输入3x-8=0和50s+180=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();
}