Name validation using IGNORECASE in Python Regex

In this article, we will learn about how to use Python Regex to validate name using IGNORECASE. re.IGNORECASE : This flag allows for case-insensitive matching of the Regular Expression with the given string i.e. expressions like [A-Z] will match lowercase letters, too. Generally, It's passed as an optional argument to re.compile(). Let's consider an example of a form where the user is asked to enter their name and we have to validate it using RegEx. The format for entering name is as follow:

• Mr. or Mrs. or Ms. (Either one) followed by a single space
• First Name, followed by a single space
• Middle Name(optional), followed by a single space
• Last Name(optional)

Examples:

Input : Mr. Albus Severus Potter 
Output : Valid

Input : Lily and Mr. Harry Potter
Output : Invalid

Note : Since, we are using IGNORECASE flag, the first character of First, Second, and Last name may or may not be capital. Below is the Python code - Python3

# Python program to validate name using IGNORECASE in RegEx

# Importing re package
import re

def validating_name(name):

    # RegexObject = re.compile( Regular expression, flag )
    # Compiles a regular expression pattern into a regular expression object
    regex_name = re.compile(r'^(Mr\.|Mrs\.|Ms\.) ([a-z]+)( [a-z]+)*( [a-z]+)*$', 
              re.IGNORECASE)

    # RegexObject is matched with the desired 
    # string using search function
    # In case a match is found, search() returns
    # MatchObject Instance
    # If match is not found, it return None
    res = regex_name.search(name)

    # If match is found, the string is valid
    if res: print("Valid")
        
    # If match is not found, string is invalid
    else: print("Invalid")

# Driver Code
validating_name('Mr. Albus Severus Potter')
validating_name('Lily and Mr. Harry Potter')
validating_name('Mr. Cedric')
validating_name('Mr. sirius black')

Output:

Valid
Invalid
Valid
valid