How do I avoid iterator invalidation with std::unordered_set?

In C++, when working with `std::unordered_set`, iterator invalidation can occur when the underlying data structure is modified. To avoid this issue, it is essential to understand how iterators work and when they become invalidated.

Here is an example that demonstrates how to safely modify an `std::unordered_set` without invalidating iterators:


        #include 
        #include 
        
        int main() {
            std::unordered_set mySet = {1, 2, 3, 4, 5};
            std::unordered_set::iterator it;

            // Create a vector to hold elements to remove
            std::vector toRemove;

            // First, gather elements to remove
            for (it = mySet.begin(); it != mySet.end(); ++it) {
                if (*it % 2 == 0) { // Remove even numbers
                    toRemove.push_back(*it);
                }
            }

            // Now, remove elements safely
            for (int num : toRemove) {
                mySet.erase(num);
            }

            // Iterators are still valid
            for (it = mySet.begin(); it != mySet.end(); ++it) {
                std::cout << *it << " ";
            }
            std::cout << std::endl;

            return 0;
        }

How do I avoid iterator invalidation with std::unordered_set?

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How do I avoid iterator invalidation with std::unordered_set?

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