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

When it is required to find sequences of an upper case letter followed by lower case using regular expression, a method named ‘match_string’ is defined that uses the ‘search’ method to match a regular expression. Outside the method, the string is defined, and the method is called on it by passing the string.

Example

Below is a demonstration of the same

import re

def match_string(my_string):

   pattern = '[A-Z]+[a-z]+$'

   if re.search(pattern, my_string):
      return('The string meets the required condition \n')
   else:
      return('The string doesnot meet the required condition \n')

print("The string is :")
string_1 = "Python"
print(string_1)
print(match_string(string_1))

print("The string is :")
string_2 = "python"
print(string_2)
print(match_string(string_2))

print("The string is :")
string_3 = "PythonInterpreter"
print(string_3)
print(match_string(string_3))

Output

The string is :
Python
The string meets the required condition
The string is :
python
The string doesn’t meet the required condition
The string is :
PythonInterpreter
The string meets the required condition

Explanation

• The required packages are imported.

• A method named ‘match_string’ is defined, that takes a string as a parameter.

• It uses the ‘search’ method to check if the specific regular expression was found in the string or not.

• Outside the method, a string is defined, and is displayed on the console.

• The method is called by passing this string as a parameter.

• The output is displayed on the console.