//
// Program name:  quadratic
// Author:  B. Massingill and students
//
// Purpose:  solve quadratic equations a*x*x + b*x + c = 0
//
// Input:  
//	sets of three floating-point numbers a,b,c, read from 
//		standard input
//	terminated by end-of-file (control-D under Unix, control-Z
//		under DOS) 
// Output:  
//	for each set of numbers:
//		if the equation has no roots, or no real roots, a
//			message to that effect
//		if the equation has one or two real roots, the root(s)
//	(written to standard output)
//
// C++ programs using math functions (such as sqrt here) begin with the 
// following four lines
#include <iostream.h>
#include <math.h>
int main()
{
	double a, b, c ;	// input coefficients

	double d ;		// b*b - 4*a*c

	// prompt user
	cout << "Enter a, b, and c; ctrl-D to end\n" ;

	// read while there is input:  
	//	"cin >> a" returns true if there is input, 
	//	false at end of file.  
	while (cin >> a)
	{
		// read in other two inputs
		cin >> b ; cin >> c ;

		// first check for a=0
		if (a == 0.0)
		{
			if (b == 0.0)
			{
				cout << "No roots\n" ;
			}
			else
			{
				cout << "One root:  " << c/b << endl ;
			}
		}
		else 
		{
			d = b*b - 4*a*c ;
			if (d < 0)
			{
				cout << "No real roots\n" ;
			}
			else if (d == 0)
			{
				cout << "One root:  " << -b /(2*a) << endl ;
			}
			else
			{
				cout << "Two roots:  " <<
					(-b + sqrt(d))/(2*a) << ", " <<
					(-b - sqrt(d))/(2*a) << endl ;
			}
			cout << "Enter a, b, and c; ctrl-D to end\n" ;
		}
	}
// C++ programs end with the following two lines.
return 0;
}