What is the difference between dict.items() and dict.iteritems() in Python?

In Python, dict.items() and dict.iteritems() are methods used to access dictionary key-value pairs. The key difference is that dict.items() returns a list of tuple pairs in Python 2 (dict_items view in Python 3), while dict.iteritems() returns an iterator over the dictionary's (key, value) pairs. Note that dict.iteritems() was removed in Python 3.

dict.items() in Python 2

In Python 2, dict.items() returns a list of tuples ?

# Python 2 syntax (cannot run online)
my_dict = {1: 'one', 2: 'two', 3: 'three', 4: 'four'}
print(my_dict.items())
print(type(my_dict.items()))

[(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]
<type 'list'>

dict.iteritems() in Python 2

In Python 2, dict.iteritems() returns an iterator for memory-efficient iteration ?

# Python 2 syntax (cannot run online)
states = {'Telangana': 'Hyderabad', 'Tamilnadu': 'Chennai', 'Karnataka': 'Bangalore'}
print(type(states.iteritems()))

for state, capital in states.iteritems():
    print(state, capital)

<type 'dictionary-itemiterator'>
('Telangana', 'Hyderabad')
('Karnataka', 'Bangalore')
('Tamilnadu', 'Chennai')

dict.items() in Python 3

In Python 3, dict.items() returns a dictionary view object ?

my_dict = {1: 'one', 2: 'two', 3: 'three', 4: 'four'}
items_view = my_dict.items()
print(items_view)
print(type(items_view))

# Convert to list if needed
print(list(items_view))

dict_items([(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')])
<class 'dict_items'>
[(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]

dict.iteritems() Error in Python 3

Using dict.iteritems() in Python 3 raises an AttributeError ?

my_dict = {"name": "Alice", "age": 21, "branch": "Computer Science"}
try:
    for item in my_dict.iteritems():
        print(item)
except AttributeError as e:
    print(f"Error: {e}")

Error: 'dict' object has no attribute 'iteritems'

Comparison

Migration from Python 2 to 3

To migrate code using iteritems(), simply replace it with items() ?

# Python 3 equivalent of iteritems()
person = {"name": "Alice", "age": 25, "city": "New York"}

# This works in Python 3 (like iteritems() in Python 2)
for key, value in person.items():
    print(f"{key}: {value}")

name: Alice
age: 25
city: New York

Conclusion

In Python 2, use iteritems() for memory-efficient iteration and items() for list operations. In Python 3, only items() exists and provides an efficient view object that behaves like the old iteritems().