String Slicing

Python’s String slicing is a versatile feature that allows you to extract a part of a string, or alter pieces of it. It’s a common operation that comes in handy when working with text data in Python.

Basic String Slicing#

In Python, strings are indexed with all the characters having an assigned number - the index. The index number starts from 0 and goes up to n-1, where n is the length of the string.

Let’s look at a string slicing example in Python:

1s = "Hello, World!"
2print(s[0:5])

In this case, the output will be Hello. The slice starts from the index position 0 (H) and goes up to the index position 4 (o), excluding the end index.

We can even omit the start or end index, and Python will slice the string from the beginning or up to the end, respectively.

1s = "Hello, World!"
2print(s[7:])
3print(s[:5])

This code will output World! and Hello, respectively.

Negative Indexing in String Slicing#

Python also supports negative indexing, which starts from the end of the string. The last character is assigned an index of -1, the second last -2, and so forth.

This is particularly useful when we want to slice a string from the end.

1s = "Hello, World!"
2print(s[-1])
3print(s[-6:-1])

This code will output ! and World, respectively.

Skipping Characters While Slicing#

In Python, we can even skip characters while slicing a string. This is done by providing a third index, known as the step value.

For example, if we want to print every second character of a string, we can do so as follows:

1s = "Hello, World!"
2print(s[::2])

This code will output Hlo ol!.

The ::2 in the square brackets tells Python to return every second character of the string s from the start to the end.

Slicing a string ’s’ in Python provides us with a new string that is a subset of ’s’. It’s a powerful way to handle and manipulate strings in Python.