Validate an IP address using Python without using RegEx

Given an IP address as input, the task is to write a Python program to check whether the given IP Address is Valid or not without using RegEx.

What is an IP (Internet Protocol) Address?

Every computer connected to the Internet is identified by a unique four-part string, known as its Internet Protocol (IP) address. An IP address (version 4) consists of four numbers (each between 0 and 255) separated by periods. The format of an IP address is a 32-bit numeric address written as four decimal numbers (called octets) separated by periods; each number can be written as 0 to 255 (E.g. – 0.0.0.0 to 255.255.255.255).

Examples:

Input:  192.168.0.1
Output: Valid IP address

Input: 110.234.52.124
Output: Valid IP address

Input: 666.1.2.2
Output: Invalid IP address

Validate an IP address using Python without using RegEx

Method #1: Checking the number of periods using count() method and then the range of numbers between each period.

Python3

# Python program to verify IP without using RegEx

# explicit function to verify IP
def isValidIP(s):

    # check number of periods
    if s.count('.') != 3:
        return 'Invalid Ip address'

    l = list(map(str, s.split('.')))

    # check range of each number between periods
    for ele in l:
        if int(ele) < 0 or int(ele) > 255 or (ele[0]=='0' and len(ele)!=1):
            return 'Invalid Ip address'

    return 'Valid Ip address'


# Driver Code
print(isValidIP('666.1.2.2'))

Output

Invalid Ip address

Method #2: Using a variable to check the number of periods and using a set to check if the range of numbers between periods is between 0 and 255(inclusive).

Python3

# Python program to verify IP without using RegEx

# explicit function to verify IP
def isValidIP(s):

    # initialize counter
    counter = 0

    # check if period is present
    for i in range(0, len(s)):
        if(s[i] == '.'):
            counter = counter+1
    if(counter != 3):
        return 0

    # check the range of numbers between periods
    st = set()
    for i in range(0, 256):
        st.add(str(i))
    counter = 0
    temp = ""
    for i in range(0, len(s)):
        if(s[i] != '.'):
            temp = temp+s[i]
        else:
            if(temp in st):
                counter = counter+1
            temp = ""
    if(temp in st):
        counter = counter+1

    # verifying all conditions
    if(counter == 4):
        return 'Valid Ip address'
    else:
        return 'Invalid Ip address'


# Driver Code
print(isValidIP('110.234.52.124'))

Output

Valid Ip address