How do I handle duplicate keys in a C++ map?

How do I handle duplicate keys in a C++ map?

In C++, the standard map does not allow duplicate keys. If you try to insert a duplicate key, it will overwrite the existing value. You can use a multimap instead, which allows multiple values for the same key.

Can you show me an example of using a multimap?

Sure! Here's a simple example:

#include <iostream>
#include <map>

int main() {
    std::multimap<int, std::string> myMap;
    myMap.insert({1, "Apple"});
    myMap.insert({1, "Banana"});
    myMap.insert({2, "Cherry"});

    for (const auto& pair : myMap) {
        std::cout << pair.first << " : " << pair.second << std::endl;
    }
    return 0;
}

What happens if I try to insert a duplicate key in a regular map?

If you insert a duplicate key in a regular map, the new value will replace the existing value associated with that key. For example:

std::map<int, std::string> myMap;
myMap[1] = "Apple";
myMap[1] = "Banana"; // This will replace "Apple" with "Banana"

Is there a way to check if a key already exists in a map?

Yes, you can use the find method to check if a key exists in a map. It returns an iterator to the element if found, or end() if not found.