// This is an example of iterator invalidation.  It creates a container,
// obtains an iterator to the one and only element in the container, and then
// invalidates the iterator.

#include <vector>
#include <iostream>

using namespace std;

int main() {
    vector<int> bunch = {253};
    vector<int>::iterator it=bunch.begin(); // Iterator refers to first int
    // or use auto

    cout << "Must be 253: " << *it << '\n';

    for (int i=1; i<10000; i++)		    // Add a whole mess of ints
	bunch.push_back(i);		    // which will force reallocation

    cout << "Probably not 253: " << *it << '\n';    // it’s been invalidated
}