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Built-in Functions

len()

Count the items in a collection or the characters in a string.

len(object)

len() returns the number of items in an object (such as a string, list, tuple, dictionary, or set).

Parameters

NameDescription
objectA sized value such as a string, list, tuple, set, or dictionary.

Returns

An integer count.

Try it

Run it and change it
words = ["red", "blue", "green"]
print(len(words))

Worth knowing

  • Constant time O(1): For Python's built-in collections, len() reads an internal size counter in O(1) time without counting elements.

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