What is a string in Python?
In Python, a string consists of an ordered sequence of characters. By default, Python 3's string type is a 16-bit byte array encoded in UTF-8. String characters can be accessed by index using square brackets "". Strings in Python are immutable; that is, once created, the string cannot be changed. Each string manipulation method returns a copy of the string and does not alter the original. The built-in "str" library has an extensive set of methods for working with strings. This library provides methods for searching, concatenating, reversing, splitting, and comparing strings.
Python String Replace Syntax
Following is the syntax of replace() method:
- old: the part of the string to replace
- new: the new substring that will replace the old substring.
- count (optional): a number indicating how many times you want to replace the old substring with the new substring. By default all occurrences will be replaced.
Python String Replace Examples
Below are examples of replacing strings in Python:
Replace all occurrences of a string in Python
The following is an example of replacing all occurrences of a string in a Python string:
Replace a specific number of occurrences of a string in Python
The following is an example of replacing a specific number of occurrences of a substring in a Python string:
Replace the first character in Python string
The following is an example of replacing the first occurrence of a substring in a Python string:
Replace all characters in Python string
The following is an example of replacing all characters in a Python string:
How to replace a Python string with a Regular Expression
Python has a built-in regular expression module that can be used to search and replace strings. To use the regex module, you must import it at the beginning of your code.
The regex module has a built-in re.sub() method for searching and replacing strings. This function takes a regex pattern, string to replace and a new value and replaces the old value with the new value using the provided pattern.
- pattern: the pattern for searching within a string with a regular expression
- replacement: the variable contains the string on which the operation is to be performed
- string: the value to be replaced with
- count (optional): the parameter specifies the maximum number of matches that the method should replace. The default value is 0
- flags (optional): the regex flags that change the default behavior of the pattern
Replacing multiple strings with Regular Expressions
The following is an example of replacing multiple patterns at the same time using a regular expression: