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  1. #include <string>
  2. #include <iostream>
  3. #include <functional>
  4. #include <algorithm>
  5. #include <list>
  6. #include <vector>
  7.  
  8. struct A
  9. {
  10.     std::string str ;
  11.     double number ;
  12.  
  13.     // ...
  14. };
  15.  
  16. std::ostream& operator << ( std::ostream& stm, const A& a )
  17. { return stm << "{'" << a.str << "'," << a.number << '}' ; }
  18.  
  19. int main()
  20. {
  21.     // const, immutable,
  22.     const std::list<A> seq_in_physical_order { { "abc", 23.67 }, { "def", 11.05 }, { "ghi", 17.32 },
  23.                                                { "jkl", 56.78 }, { "mno", 33.12 }, { "pqr", 40.71 } } ;
  24.  
  25.     std::vector< std::reference_wrapper< const A > > seq_in_logical_order( seq_in_physical_order.begin(),
  26.                                                                    seq_in_physical_order.end() ) ;
  27.     // perform a logical ordering with respect to the member 'number'
  28.     std::sort( seq_in_logical_order.begin(), seq_in_logical_order.end(),
  29.                [] ( const A& first, const A& second ) { return first.number < second.number ; }  ) ;
  30.  
  31.     std::cout << "in physical order:\n-----------------\n" ;
  32.     for( const A& a : seq_in_physical_order ) std::cout << a << " @ " << std::addressof(a) << '\n' ;
  33.  
  34.     std::cout << "\n\n\nin logical order:\n----------------\n" ;
  35.     for( const A& a : seq_in_logical_order ) std::cout << a << " @ " << std::addressof(a) << '\n' ;
  36.     std::cout << '\n' ;
  37.  
  38. }
  39.  
Success #stdin #stdout 0s 3476KB
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stdin
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Standard input is empty
stdout
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in physical order:
-----------------
{'abc',23.67} @ 0x92d70a0
{'def',11.05} @ 0x92d70b8
{'ghi',17.32} @ 0x92d70d0
{'jkl',56.78} @ 0x92d70e8
{'mno',33.12} @ 0x92d7100
{'pqr',40.71} @ 0x92d7118



in logical order:
----------------
{'def',11.05} @ 0x92d70b8
{'ghi',17.32} @ 0x92d70d0
{'abc',23.67} @ 0x92d70a0
{'mno',33.12} @ 0x92d7100
{'pqr',40.71} @ 0x92d7118
{'jkl',56.78} @ 0x92d70e8
https://ideone.com/ENfmE6
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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