demo_1_io_simple.cpp

对于一个初涉VC＋＋的人来书

//***************************************************
// 标准输入输出流: cin cout cerr clog
//***************************************************

//# include <iostream.h>
//# include <math.h>

# include <iostream>
# include <cmath>
using namespace std;

int main()
{
	float a,b,c,disc;

	cout<<"please input a,b,c:";
	cin>>a>>b>>c;

	if (a==0)
		cerr<<"a is equal to zero,error!"<<endl;
	else
	{
		if ((disc=b*b-4*a*c)<0)
			cerr<<"disc=b*b-4*a*c<0"<<endl;
		else
		{
			cout<<"x1="<<(-b+sqrt(disc))/(2*a)<<endl;
			cout<<"x2="<<(-b-sqrt(disc))/(2*a)<<endl;   
		}
	}

	return 0;
}