Python: Matches a string that has an a followed by zero or one 'b'

Last update on April 23 2025 12:54:25 (UTC/GMT +8 hours)

4. a Followed by 0 or 1 b

Write a Python program that matches a string that has an a followed by zero or one 'b'.

Sample Solution:

Python Code:

import re
def text_match(text):
        patterns = 'ab?'
        if re.search(patterns,  text):
                return 'Found a match!'
        else:
                return('Not matched!')

print(text_match("ab"))
print(text_match("abc"))
print(text_match("abbc"))
print(text_match("aabbc"))

Sample Output:

Found a match!                                                                                                
Found a match!                                                                                                
Found a match!                                                                                                
Found a match!

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to verify if a string starts with 'a' and is optionally followed by a single 'b', using regex.
• Write a Python script to filter a list of strings, returning only those that match the pattern where 'a' is optionally followed by one 'b'.
• Write a Python program to test if an input string conforms to the regex pattern 'ab?' and print an appropriate message.
• Write a Python program to extract from a text all occurrences of the pattern where 'a' is followed by zero or one 'b'.

Go to:

• Python Regular Expression Exercises Home ↩
• Python Exercises Home ↩

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Python Code Editor:

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