Python 3 reference · Built-in Functions

Python slice() Function

Create a slice object, the thing behind a[start:stop:step]. Useful to name and reuse a slice.

Syntax

slice(stop)
slice(start, stop, step=None)

Parameters

Parameter	Description
`start` optional	Start index. Default: `None`
`stop`	Stop index (not included).
`step` optional	Step between items. Default: `None`

Return value

A slice object.

Examples

Reusable slicesTry it yourself

letters = "abcdefgh"
first_three = slice(3)
every_other = slice(None, None, 2)
print(letters[first_three], letters[every_other])

Output

abc aceg

Name the fields of fixed-width textTry it yourself

record = "2026-10-21 ERROR disk full"
DATE, LEVEL, MESSAGE = slice(0, 10), slice(11, 16), slice(17, None)
print(record[DATE], "|", record[LEVEL], "|", record[MESSAGE])

Output

2026-10-21 | ERROR | disk full

Good to know

Slice objects are hashable since Python 3.12, so they can be dictionary keys.

Version history

Version	Change
Python 3.0	Added
Python 3.12	Slice objects became hashable.

range() · Create an immutable sequence of integers from start up to (but not including) stop, in steps. Used in for loops.
list() · Create a list: an ordered, changeable sequence. Called with an iterable, it copies its items into a new list.
Python Strings · tutorial
Python Lists · tutorial