第七周项目1-解出一个一元二次方程的两个根

/*
* Copyright (c) 2014,烟台大学计算机学院
* All right reserved.
* 作者：邵帅
* 文件：temp.cpp
* 版本号：v1.0
*/
#include<iostream>
#include<math.h>
using namespace std;
int main()
{
	cout << "请输入a,b,c值:" << endl;
	cout << "例如：x²+3x-2=0" << endl;
	cout << "a=1 b=3 c=2" << endl;
	cout << "--------------------------" << endl;
	cout << "请输入:" << endl;
	float a, b, c, d, x1, x2;	/* 定义变量 */
	cin >> a >> b >> c;			/* 输入一元二次方程的三个参数 */
	if (a != 0)
	{
		d = b * b - 4 * a * c;	// 判断德它
		if (d > 0)
		{
			x1 = (-b + sqrt(d)) / 2 * a;
			x2 = (-b - sqrt(d)) / 2 * a;
			cout << "方程根为:" << "x1=" << x1 << "    x2=" << x2;
		}
		else if (d == 0)
		{
			x1 = -b / (2 * b);
			cout << "方程根为:x1=x2=" << x1;
		}
		else
		{
			cout << "无实根!";
		}
	}
	else if (a == 0)
	{
		cout << "非一元二次方程!";
	}
	return 0;
}