How do I remove duplicates with std::multimap?

In C++, std::multimap allows for the storage of multiple values under the same key. However, if you want to remove duplicates from a std::multimap, you can do so by using an algorithm to traverse the multimap and erase duplicate entries. Below is an example demonstrating how to remove duplicates from a std::multimap.


#include <iostream>
#include <map>
#include <set>

int main() {
    // Create a multimap and insert some duplicate entries
    std::multimap m;
    m.insert(std::make_pair(1, "apple"));
    m.insert(std::make_pair(1, "apple")); // duplicate
    m.insert(std::make_pair(2, "banana"));
    m.insert(std::make_pair(3, "orange"));
    m.insert(std::make_pair(3, "orange")); // duplicate

    // Use a set to track unique entries
    std::set<:pair std::string>> uniqueEntries;

    // Traverse the multimap and insert only unique entries into the set
    for (const auto& entry : m) {
        uniqueEntries.insert(entry);
    }

    // Clear the original multimap
    m.clear();

    // Insert back only the unique entries
    for (const auto& entry : uniqueEntries) {
        m.insert(entry);
    }

    // Print the multimap after removing duplicates
    for (const auto& entry : m) {
        std::cout << entry.first << ": " << entry.second << std::endl;
    }

    return 0;
}

How do I remove duplicates with std::multimap?

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How do I remove duplicates with std::multimap?

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