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  1. #include <map>
  2. #include <iostream>
  3.  
  4. using Operator = double(double, double);
  5.  
  6. double plus(double x, double y) {
  7.     return x+y;
  8. }
  9.  
  10. double minus(double x, double y) {
  11.     return x-y;
  12. }
  13.  
  14. double divide(double x, double y) {
  15.     return x/y;
  16. }
  17.  
  18. double multiply(double x, double y) {
  19.     return x*y;
  20. }
  21.  
  22. int main()
  23. {
  24.     std::map<char, Operator&> operators = {
  25.         {'+', plus},
  26.         {'-', minus},
  27.         {'/', divide},
  28.         {'*', multiply}
  29.     };
  30.     double x = 0;
  31.     double y = 0;
  32.     char op = 0;
  33.     double result = 0;
  34.     std::cout << "Input number, operation (+, -, /, *) and number, please: ";
  35.     std::cin >> x >> op >> y;
  36.     const auto operation = operators.find(op);
  37.     if (operation != operators.cend())
  38.         std::cout << "Result: " << (*operation->second)(x, y) << '\n';
  39.     else
  40.         std::cout << "Operation " << op << " not found!\n";
  41.     return 0;
  42. }
Success #stdin #stdout 0s 3464KB
comments (?)
stdin 
123 / 3
stdout 
Input number, operation (+, -, /, *) and number, please: Result: 41
https://ideone.com/5MJVkM
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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