3.1.4.3 Lists - collections of data | Indexing

Accessing list content

Each of the list's elements may be accessed separately. For example, it can be printed:

print(numbers[0]) # accessing the list's first element

Assuming that all of the previous operations have been completed successfully, the snippet will send 111 to the console.

As you can see in the editor, the list may also be printed as a whole - just like here:

print(numbers) # printing the whole list

As you've probably noticed before, Python decorates the output in a way that suggests that all the presented values form a list. The output from the example snippet above looks like this:

[111, 1, 7, 2, 1]

The len() function

The length of a list may vary during execution. New elements may be added to the list, while others may be removed from it. This means that the list is a very dynamic entity.

If you want to check the list's current length, you can use a function named len() (its name comes from length).

The function takes the list's name as an argument, and returns the number of elements currently stored inside the list (in other words - the list's length).

Look at the last line of code in the editor, run the program and check what value it will print to the console. Can you guess?

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numbers = [10, 5, 7, 2, 1]

print("Original list content:", numbers) # printing original list content

numbers[0] = 111

print("\nPrevious list content:", numbers) # printing previous list content

numbers[1] = numbers[4] # copying value of the fifth element to the second

print("Previous list content:", numbers) # printing previous list content

print("\nList length:", len(numbers)) # printing the list's length

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