How to use the Python String replace() Method

John on September 18, 2020

The Python string replace() method is used to find substrings in a string and replace them with a new value (or an empty string).

In this tutorial, we will learn how to search for occurrences of a substring and replace them with a new string.

String replace() Syntax

The syntax of replace() is:

string.replace(old, new, [limit])

replace() is always placed after the string to search in using a . (dot). It uses two required arguments and one optional argument:

• old - the substrings to replace wrapped in '' (single quotations) or "" (double quotations)
• new -  the new string to replace occurrences of old with wrapped in '' (single quotations) or "" (double quotations)
• limit - the maximum number of occurrences to replace (optional)

Basic Usage

Let's replace all occurrences of a word in a string with a new word. replace() returns a new string with the updated values, which we will store in a variable before printing the final result.

string = "two plus two is... three plus three is..."

new_str = string.replace('two', 'four')

print(new_str)

four plus four is... three plus three is...

Replace only the First Occurance in a String

To replace only the first substring or another limited number of matches, pass the number in the third argument of replace().

string = "two plus two is... three plus three is..."

new_str = string.replace('two', 'four', 1)

print(new_str)

four plus two is... three plus three is...

Replace Characters in a String

replace() can be used to replace individual characters in a string.

string = "col cop"

new_str = string.replace('o', 'a')

print(new_str)

cal cap

Conclusion

You now know how to replace substrings of a string in Python.