《第九周实验报告任务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):a(aa),b(bb){ }
	friend istream &operator >> (istream &in,CEquation &e);
	friend ostream &operator << (ostream &out,CEquation &e);
	double Solve();
	char getUnknown();
};

istream &operator >> (istream &in,CEquation &e)
{
	char f,x,y;

	do
	{
	in >> e.a >> e.unknown >> f >> e.b >> x >>y;//char型只包含一个字符

	if(f == '-')
	{
         e.b=-e.b;
	}

	if((x == '=' && y == '0' && f == '+')||(x == '=' && y == '0' && f == '-'))
	{
		
		break;
	}
	else
	{
		cout << "输入不合法，请重新输入：" ;

	}

	}while(1);

	return in;
}
ostream &operator << (ostream &out,CEquation &e)
{
	out << e.a << e.unknown << e.b << "=0";

	return out;
}

double CEquation::Solve()
{
	double x;

	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)" << endl;

	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=...

	system("pause");

	return 0;
}