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  1. #include <iostream>
  2. #include <string>
  3. #include <boost/multi_index_container.hpp>
  4. #include <boost/multi_index/ordered_index.hpp>
  5. #include <boost/multi_index/member.hpp>
  6.  
  7. using namespace boost::multi_index;
  8.  
  9. // Define a structure for the data
  10. struct Book {
  11.     int rank;
  12.     std::string value;
  13.  
  14.     Book(int rank, const std::string& value) : rank(rank), value(value) {}
  15. };
  16.  
  17. // Define tags to reference the indices
  18. struct rank_tag {};
  19.  
  20. // Define a multi-index container for Book struct
  21. typedef multi_index_container<
  22.     Book,
  23.     indexed_by<
  24.         ordered_unique<
  25.             tag<rank_tag>,    // Index by book rank
  26.             member<Book, int, &Book::rank>
  27.         >
  28.     >
  29. > BookMultiIndex;
  30.  
  31. // Function to insert a book and adjust ranks
  32. void insert_book(BookMultiIndex& books, int rank, const std::string& value) {
  33.     // Access by rank index
  34.     auto& rank_index = books.get<rank_tag>();
  35.  
  36.     // Adjust ranks for books with rank >= the new rank
  37.     for (auto it = rank_index.lower_bound(rank); it != rank_index.end(); ++it) {
  38.         rank_index.modify(it, [](Book& b) {
  39.             ++b.rank;
  40.         });
  41.     }
  42.  
  43.     // Insert the new book
  44.     books.insert(Book(rank, value));
  45. }
  46.  
  47. // Function to delete a book and adjust ranks
  48. void delete_book(BookMultiIndex& books, int rank) {
  49.     // Access by rank index
  50.     auto& rank_index = books.get<rank_tag>();
  51.  
  52.     // Find the book to delete
  53.     auto it = rank_index.find(rank);
  54.     if (it != rank_index.end()) {
  55.         // Erase the book
  56.         rank_index.erase(it);
  57.  
  58.         // Adjust ranks for books with rank > the deleted rank
  59.         for (auto it2 = rank_index.lower_bound(rank + 1); it2 != rank_index.end(); ++it2) {
  60.             rank_index.modify(it2, [](Book& b) {
  61.                 --b.rank;
  62.             });
  63.         }
  64.     }
  65. }
  66.  
  67. // Function to print all elements
  68. void print_all(const BookMultiIndex& books) {
  69.     auto& rank_index = books.get<rank_tag>();
  70.     std::cout << "Books in the container:" << std::endl;
  71.     for (const auto& book : rank_index) {
  72.         std::cout << "Rank = " << book.rank << ", Value = " << book.value << std::endl;
  73.     }
  74. }
  75.  
  76. int main() {
  77.     // Create the multi-index container
  78.     BookMultiIndex books;
  79.  
  80.     // Insert data into the container
  81.     books.insert(Book(1, "a"));
  82.     books.insert(Book(2, "b"));
  83.     books.insert(Book(3, "c"));
  84.     books.insert(Book(4, "d"));
  85.  
  86.     // Print initial state
  87.     print_all(books);
  88.  
  89.     // Insert a new book at rank 2
  90.     insert_book(books, 2, "f");
  91.     std::cout << "\nAfter inserting at rank 2:" << std::endl;
  92.     print_all(books);
  93.  
  94.     // Delete the book at rank 2
  95.     delete_book(books, 2);
  96.     std::cout << "\nAfter deleting rank 2:" << std::endl;
  97.     print_all(books);
  98.  
  99.     return 0;
  100. }
  101.  
Success #stdin #stdout 0s 5288KB
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Standard input is empty
stdout
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Books in the container:
Rank = 1, Value = a
Rank = 2, Value = b
Rank = 3, Value = c
Rank = 4, Value = d

After inserting at rank 2:
Books in the container:
Rank = 2, Value = f
Rank = 3, Value = a
Rank = 5, Value = d

After deleting rank 2:
Books in the container:
Rank = 2, Value = a
Rank = 4, Value = d
https://ideone.com/MWUM3g
language:
C++14 (gcc 8.3)
created:
4 days ago
visibility:
public

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