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Python regex to find sequences of one upper case letter followed by lower case letters

Python regex to find sequences of one upper case letter followed by lower case letters

Last Updated : 06 Sep, 2024

Write a Python Program to find sequences of one upper case letter followed by lower case letters. If found, print 'Yes', otherwise 'No'.

Examples:

Input : Geeks
Output : Yes
Input : geeksforgeeks
Output : No

Python regex to find sequences of one upper case letter followed by lower case letters

Using re.search() To check if the sequence of one upper case letter followed by lower case letters we use regular expression '[A-Z]+[a-z]+$'.

Python

import re  def findSequence(text):   	# regex pattern     pattern = '[A-Z][a-z]+'          # Use re.search to find any match     if re.search(pattern, text):         return 'Yes'     else:         return 'No'  # Driver program if __name__ == "__main__":     word = 'geeAkAA55of55gee4ksabc3Ar2x'     print(findSequence(word))     word = 'Geeks'     print(findSequence(word))     word = 'geeksforgeeks'     print(findSequence(word))

Output:

Yes
Yes
No

Time complexity: O(n), where n is length of string.
Auxiliary Space: O(1)

Find those sequences of one upper case letter followed by lower case letters

To find and print all sequences of one uppercase letter followed by lowercase letters in the given text we can use the re.findall() function.

Here's how we can do it:

Python

import re  def findSequences(text):   	#regex pattern     pattern = r'[A-Z][a-z]+'     return re.findall(pattern, text)  # Driver program if __name__ == "__main__":     word = 'geeAkAA55of55gee4ksabc3Ar2x'     print(findSequences(word))     word = 'Geeks'     print(findSequences(word))     word = 'geeksforgeeks'     print(findSequences(word))

Output:

['Ak', 'Ar']
['Geeks']
[]

Time Complexity: O(n) where n is the length of the input text.

Auxiliary Space Complexity: O(k) where k is the number of matches found.

Python regex to find sequences of one upper case letter followed by lower case letters

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Smitha Dinesh Semwal

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