How do I erase elements while iterating with std::unordered_map in performance-sensitive code?

When iterating through a `std::unordered_map` in C++, you may need to erase elements based on certain conditions. However, erasing elements while iterating can invalidate the iterator, leading to undefined behavior. To safely erase elements during iteration in a performance-sensitive context, you should use the `erase` function with the iterator returned by the `find` method or by using a temporary iterator. Here's how you can do it:


        #include 
        #include 

        int main() {
            std::unordered_map myMap = {
                {1, "one"},
                {2, "two"},
                {3, "three"},
                {4, "four"}
            };

            for (auto it = myMap.begin(); it != myMap.end(); ) {
                if (it->first % 2 == 0) { // Erase even keys
                    it = myMap.erase(it); // erase returns the next iterator
                } else {
                    ++it; // Increment iterator
                }
            }

            // Output remaining elements
            for (const auto& pair : myMap) {
                std::cout << pair.first << ": " << pair.second << std::endl;
            }

            return 0;
        }

std::unordered_map erase iterator performance C++

How do I erase elements while iterating with std::unordered_map in performance-sensitive code?

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How do I erase elements while iterating with std::unordered_map in performance-sensitive code?

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