#include "library.h"

void solve_quadratic(double A, double B, double C)
// solve Ax2 + Bx + C = 0 and print all solutions;
{ const double det = B*B - 4*A*C;
  if (det < 0)
    print("No solutions\n");
  else if (det == 0)
  { print("X = ");
    print(-B/(2*A));
    new_line(); }
  else
  { const double sqrt_det = sqrt(det);
    print("X = ");
    print((-B+sqrt_det)/(2*A));
    new_line();
    print(" or ");
    print((-B-sqrt_det)/(2*A));
    new_line(); } }

void interact()
{ print("Enter A and B and C: ");
  const double A = read_double();
  const double B = read_double();
  const double C = read_double();
  solve_quadratic(A, B, C); }

bool ask_again()
{ print("Solve another equation? ");
  const string answer = read_string();
  if (answer == "yes")
    return true;
  if (answer == "no")
    return false;
  return ask_again(); }

void do_tests()
{ if (ask_again())
  { interact();
    do_tests(); } }

void main()
{ interact();
  do_tests(); }