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  1. #include <iostream>
  2. #include <functional>
  3.  
  4. using namespace std;
  5.  
  6. typedef double R;
  7.  
  8. auto f( std::array<R, 3> &p ) -> R {
  9.     return p[ 0 ] + 2 * p[ 1 ] + 3 * p[ 2 ];
  10. };
  11.  
  12. class Ftor
  13. {
  14. 	int idx;
  15. 	R (*func)( std::array<R, 3> &p );
  16. public:
  17. 	Ftor( int _idx, R (*_func)( std::array<R, 3> &p ) ): idx( _idx ), func( _func ) {};
  18. 	R operator()( R x )
  19. 	{
  20. 		std::array<R, 3> p = { 0, 0, 0 };	
  21. 		p[ idx ] = x;
  22. 		return func( p );
  23. 	}
  24. };
  25.  
  26. auto main() -> int {
  27. 	Ftor fx{ 0, f };
  28. 	Ftor fy{ 1, f };
  29. 	Ftor fz{ 2, f };
  30.  
  31.     cout << fx( 5 ) << endl; // 5
  32.     cout << fy( 5 ) << endl; // 10
  33.     cout << fz( 5 ) << endl; // 15
  34.  
  35.     return 0;
  36. }
  37.  
Success #stdin #stdout 0s 15232KB
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Standard input is empty
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5
10
15
https://ideone.com/4cfjdZ
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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