第十四周阅读程序——例一

#include <iostream>
#include <math.h>
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;
}