Summary: in this tutorial, you’ll learn how to use the Python string replace() method to replace some or all occurrences of a substring with a new substring.

Introduction to the Python string replace() method

The replace() method returns a copy of a string with some or all matches of a substring replaced with a new substring.

The following shows the syntax of the replace() method:

The replace() method accepts three parameters:

• substr is a string that is to be replaced by the new_substr.
• new_substr is the string that replaces the substr
• count is an integer that specifies the first count number of occurrences of the substr that will be replaced with the new_substr. The count parameter is optional. If you omit the count argument, the replace() method will replace all the occurrences of the substr by the new_substr.

It’s important to note that the replace() method returns a copy of the original string with some or all occurrences of the substr replaced by the new_substr. It doesn’t change the original string.

Python string replace() method examples

Let’s take some examples of using the replace() method.

1) Replacing all occurrences of a substring with a new substring

The following example uses the string replace() method to replace all occurrences of the substring 'We' by the new substring 'Python':

Code language: PHP (php)

Output:

2) Replacing some occurrences of a substring by a new substring

The following example uses the replace() method to replace the first occurrence of the substring 'bye' by the new substring 'baby':

Code language: PHP (php)

Output:

In this example, we passed the count argument as one. Therefore, the replace() method just replaces the first occurrence of the string 'bye' with the string 'baby'

Summary

• Use the Python string replace() method to return a copy of a string with some or all occurrences of a substring replaced by a new substring.