The difference between iteriitems and items in sorted

If you want to get the descending ranking of the scores of each subject in dictionary a, the code is as follows.

a = {'math':98, 'english':100, 'PE':77}
b = sorted(a.iteritems(), key=operator.itemgetter(1), reverse=True)
c = sorted(a.items(), key=operator.itemgetter(1), reverse=True)

Both b and c can output the desired results, but what is the difference between these two methods in terms of operating mechanism and efficiency?

In fact, iteritems()Returns a generator that can traverse all key-value pairs

items()Returns a copy of the key-value pairs in the entire list. When the dict is relatively large, it will consume a lot of memory.

The items() in python3 is changed to the behavior of iteritems() and then Deletediteritems()

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