Python slice string

Python slice string syntax is:

The slicing starts with the start_pos index (included) and ends at end_pos index (excluded). The step parameter is used to specify the steps to take from start to end index.

Python String slicing always follows this rule: s[:i] + s[i:] == s for any index ‘i’.

All these parameters are optional – start_pos default value is 0, the end_pos default value is the length of string and step default value is 1.

Let’s look at some simple examples of string slice function to create substring.

Output:

Note that since none of the slicing parameters were provided, the substring is equal to the original string.

Let’s look at some more examples of slicing a string.

Output:

Note that index value starts from 0, so start_pos 2 refers to the third character in the string.

Reverse a String using Slicing

We can reverse a string using slicing by providing the step value as -1.

Output: dlroWolleH

Let’s look at some other examples of using steps and negative index values.

Output: loo

Here the substring contains characters from indexes 2,4 and 6.

Output: lroWoll

Here the index values are taken from end to start. The substring is made from indexes 1 to 7 from end to start.

Output: lool

Python slice works with negative indexes too, in that case, the start_pos is excluded and end_pos is included in the substring.

Output: or

Python string slicing handles out of range indexes gracefully.

That’s all for python string slice function to create substring.