fork(2) download
copy 
  1. #include <iostream>
  2. #include <unordered_map>
  3. #include <string>
  4. #include <cmath>
  5. using namespace std;
  6.  
  7. class Calculator {
  8. private:
  9.     typedef double (Calculator::*FuncType)(double, double);
  10.  
  11.     unordered_map<string, FuncType> operator_function = {
  12.         {"*",  &Calculator::multiply},
  13.         {"^",  &Calculator::exponent},
  14.         {"**", &Calculator::exponent}
  15.         // and so on ...
  16.     };
  17.  
  18.     double multiply(double num_1, double num_2) {
  19.         cout << "MULTIPLYING!" << endl;
  20.         return num_1 * num_2;
  21.     }
  22.  
  23.     double exponent(double num_1, double num_2) {
  24.         cout << "EXPONENT!" << endl;
  25.         return pow(num_1, num_2);
  26.     }
  27.  
  28. public:
  29.     double do_math(string op, double num_1, double num_2) {
  30.         FuncType func = operator_function[op]; 
  31.         return (this->*func)(num_1, num_2);
  32.     }
  33. };
  34.  
  35. int main() {
  36. 	Calculator calc;
  37. 	cout << calc.do_math("*", 123, 45) << endl;
  38. 	cout << calc.do_math("^", 123, 2) << endl;
  39. 	return 0;
  40. }
Success #stdin #stdout 0.01s 5492KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
MULTIPLYING!
5535
EXPONENT!
15129
https://ideone.com/jiLfNm
language:
C++ 4.3.2 (gcc-4.3.2)
created:
2 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!