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  1. #include <iostream>
  2. #include <cassert>
  3. #include <cmath>
  4.  
  5. bool solve_quadratic(double a, double b, double c, double& x1, double& x2)
  6. {
  7.     assert(a != 0);
  8.  
  9.     const double delta = b * b - 4 * a * c;
  10.     if (delta < 0) {
  11.         return false;
  12.     }
  13.     if (delta == 0) {
  14.         x1 = -b / (2 * a);
  15.         x2 = x1;
  16.     } else {
  17.         const double sqrt_delta = sqrt(delta);
  18.         x1 = (-b + sqrt_delta) / (2 * a);
  19.         x2 = (-b - sqrt_delta) / (2 * a);
  20.     }
  21.     return true;
  22. }
  23.  
  24. void output_result_of_quadratic(double a, double b, double c)
  25. {
  26.     double x1;
  27.     double x2;
  28.  
  29.     std::cout << "For : " << a << " x^2 + " << b << " x + " << c << " = 0" << std::endl;
  30.     if (solve_quadratic(a, b, c, x1, x2)) {
  31.         if (x1 == x2) {
  32.             std::cout << "The only solution is x: " << x1 << std::endl;
  33.         } else {
  34.             std::cout << "The solutions are : "<< x1 << " and " << x2 << std::endl;
  35.         }
  36.     } else {
  37.         std::cout << "No real solution." << std::endl;
  38.     }
  39. }
  40.  
  41. int main()
  42. {
  43.     output_result_of_quadratic(1, -2, 1); // 1
  44.     output_result_of_quadratic(1, 0, 1);  // complex
  45.     output_result_of_quadratic(1, -5, 6);  // 2, 3
  46.  
  47.     return 0;
  48. }
  49.  
Success #stdin #stdout 0s 3300KB
comments (?)
stdin 
Standard input is empty
stdout 
For : 1 x^2 + -2 x + 1 = 0
The only solution is x: 1
For : 1 x^2 + 0 x + 1 = 0
No real solution.
For : 1 x^2 + -5 x + 6 = 0
The solutions are : 3 and 2
https://ideone.com/o8nLlV
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
secret

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