How do I merge and splice sequences with std::unordered_map?

In C++, merging and splicing sequences using `std::unordered_map` involves combining key-value pairs from multiple unordered maps or modifying the existing pairs without the need for copying elements. This enables efficient manipulation of associative containers.

Example: Merging Unordered Maps

#include <iostream> #include <unordered_map> int main() { std::unordered_map<std::string, int> map1 = { {"apple", 1}, {"banana", 2} }; std::unordered_map<std::string, int> map2 = { {"banana", 3}, // this will update map1's value {"cherry", 4} }; // Merging map2 into map1 for (const auto &pair : map2) { map1[pair.first] += pair.second; // Splicing values } // Output the merged map for (const auto &pair : map1) { std::cout << pair.first << ": " << pair.second << std::endl; } return 0; }

C++ std::unordered_map merge splice sequences associative containers key-value pairs

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