fork(1) download
copy 
  1. #include <iostream>
  2. using namespace std;
  3.  
  4. template<typename T>
  5.     struct relational
  6.     {
  7.         friend bool operator> (T const &lhs, T const &rhs) { return rhs < lhs; }
  8.         friend bool operator==(T const &lhs, T const &rhs) { return !(lhs < rhs || lhs > rhs); }
  9.         friend bool operator!=(T const &lhs, T const &rhs) { return !(rhs == lhs); }
  10.         friend bool operator<=(T const &lhs, T const &rhs) { return !(rhs < lhs); }
  11.         friend bool operator>=(T const &lhs, T const &rhs) { return !(lhs < rhs); }
  12.     };
  13.  
  14.     struct foo : relational<foo>
  15.     { 
  16.     	int a;
  17.     	foo(int a) : a(a) {}
  18.       friend bool operator<(foo const &f1, foo const &f2)
  19.       {
  20.       	return f1.a < f2.a;
  21.       }
  22.     };
  23.  
  24. int main() {
  25. 	foo f1(1), f2(2);
  26.  
  27. 	cout << (f1 == f2) << endl;
  28. 	cout << (f2 > f1) << endl;
  29. 	return 0;
  30. }
Success #stdin #stdout 0s 3296KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
0
1
https://ideone.com/Ck7Z6k
language:
C++14 (gcc 8.3)
created:
10 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!