Lecture 96:- Reverse A String RE

To reverse a string using regular expressions (RE), you can use the re.sub() function from Python's re module. The idea is to use a regular expression to match every character in the string and replace it with the reverse of the string.

Here's a Python code snippet to reverse a string using regular expressions:

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import re def reverse_string_with_re(input_string):    # Use a regular expression to match every character in the string and capture it in a group    # The regular expression pattern '(.*)' matches the entire string and captures it in group 1    # The replacement pattern '\1' refers to the captured group 1 (i.e., the entire string)    reversed_string = re.sub(r'(.*)', r'\1', input_string[::-1])    return reversed_string # Test the function input_string = "Hello, World!" reversed_string = reverse_string_with_re(input_string) print(reversed_string)

Output:

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!dlroW ,olleH

In this example, the re.sub() function takes a regular expression pattern as the first argument, and the replacement pattern as the second argument. The pattern (.*) captures the entire string and stores it in group 1. The replacement pattern \1 refers to group 1, effectively reversing the captured string. The input_string[::-1] is used to reverse the original string before applying the regular expression substitution.