#include <stdio.h>
#include <math.h>

typedef struct {
  double a;
  double b;
  double c;
} equationSecondDegre;

double calculerY(equationSecondDegre e, double x) {
  return e.a * x * x + e.b * x + e.c;
}

void afficherEquationSecondDegre(equationSecondDegre e) {
  printf("f(x) = %lf x2 + %lf x + %lf", e.a, e.b, e.c);
}

double calculerDelta(equationSecondDegre e) {
  return e.b * e.b - 4.0 * e.a * e.c;
}

int calculerRacines(equationSecondDegre e,double *r1,double *r2) {
  double delta = calculerDelta(e);
  if (delta < 0.0) {
    return 0;
  }
  if (delta < 0.0) {
    *r1 = -e.b / (2.0 * e.a);
    return 1;
  }
  double sqrtDelta = sqrt(delta);
  *r1 = (-e.b - sqrtDelta) / (2.0 * e.a);
  *r2 = (-e.b + sqrtDelta) / (2.0 * e.a);
  return 2;
}

int main(void) {
  equationSecondDegre eq = { 1.2,-2.3,-6.4 };
  afficherEquationSecondDegre(eq);
  printf("\n");
  printf("\n");
  printf("Pour x = %lf, f(x) = %lf\n", 2.3, calculerY(eq, 2.3));
  printf("\n");
  double r1;
  double r2;
  int nbRacines = calculerRacines(eq, &r1, &r2);
  switch (nbRacines) {
    case 0: {
      printf("La fonction f n'a pas de racine reelle\n");
    }
    break;
    case 1: {
      printf("La fonction f a une racine reelle : %lf\n", r1);
      printf("Pour x = %lf, f(x) = %lf\n", r1, calculerY(eq, r1));
    }
    break;
    case 2: {
      printf("La fonction f a deux racines reelles : %lf et %lf\n", r1, r2);
      printf("Pour x = %lf, f(x) = %lf\n", r1, calculerY(eq, r1));
      printf("Pour x = %lf, f(x) = %lf\n", r2, calculerY(eq, r2));
    }
    break;
  }
  return 0;
}