How to use range-based for() loop with std::map?

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Each element of the container is a map<K, V>::value_type, which is a typedef for std::pair<const K, V>. Consequently, in C++17 or higher, you can write

for (auto& [key, value]: myMap) {
    std::cout << key << " has value " << value << std::endl;
}

or as

for (const auto& [key, value]: myMap) {
    std::cout << key << " has value " << value << std::endl;
}

if you don’t plan on modifying the values.

In C++11 and C++14, you can use enhanced for loops to extract out each pair on its own, then manually extract the keys and values:

for (const auto& kv : myMap) {
    std::cout << kv.first << " has value " << kv.second << std::endl;
}

You could also consider marking the kv variable const if you want a read-only view of the values.

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