/*
 * Author: Simon Schurti
 *
 * Licence: MIT
 *
 * Informatik 1 exercice:
 * Takes user input for Voltage and Current in V/A respectively.
 * calculates and prints Power and Resistance
 */

#include <stdio.h>
int main() {
  double u, i, p, r; // Voltage , current, power, resistance
  while (1) {
    printf("To Terminate enter anything that is not a valid float.\n\n");

    // fscanf returns bytes scanned, so  if ret is 0 no float was detected
    // fscanf only matches %lf, so "123 asdlkj" would be valid input according
    // to format specified in fscanf. getc pops next byte from stdin, which is
    // always \n if user input is valid
    printf("Voltage[V]: ");
    int ret = fscanf(stdin, "%lf", &u); // read voltage from user
    if (ret <= 0 || getc(stdin) != '\n')
      break; // terminate if user input is invalid
    printf("Current[A]: ");
    ret = fscanf(stdin, "%lf", &i); // read current form user
    if (ret <= 0 || getc(stdin) != '\n')
      break; // termainte if user input is invalnid

    // power [W] = current [A] * voltage[V]
    p = i * u;

    // resistance[Ohm] = voltage[V] / current[A]
    if (i != 0) {
      r = u / i;
      printf("Resistance[Ohm]: %.3lf\n", r);
      printf("Power[W]: %.3lf\n", p);
      printf("Resistance %.3lf  is %s than Power %.3lf\n", r,
             (r > p) ? "greater" : "smaller", p);
    } else {
      printf("No current is flowing. Resistance cannot be "
             "calculated\nPower: 0 W\n");
    }
  }
  return 0;
}