Regex | Alien Username

on

In a galaxy far, far away, on a planet different from ours, each computer username uses the following format:

  1. It must begin with either an underscore, _ (ASCII value ), or a period, . (ASCII value ).
  2. The first character must be immediately followed by one or more digits in the range 0 through 9.
  3. After some number of digits, there must be 0 or more English letters (uppercase and/or lowercase).
  4. It may be terminated with an optional _.

Given n strings, determine which ones are valid alien usernames. If a string is a valid alien username, print VALID on a new line; otherwise, print INVALID.

Input Format

The first line contains a single integer, n , denoting the number of usernames.
Each line i of the n subsequent lines contains a string denoting an alien username to validate.

Constraints

  • 1 <= n <= 100

Output Format

Iterate through each of the n strings in order and determine whether or not each string is a valid alien username. If a username is a valid alien username, print VALID on a new line; otherwise, print INVALID.

Sample Input

3
_0898989811abced_
_abce
_09090909abcD0

Sample Output

VALID
INVALID
INVALID

Explanation

We validate the following three usernames:

  1. _0898989811abced_ is valid as it satisfies the requirements specified above. Thus, we print VALID.
  2. _abce is invalid as the beginning _ is not followed by one or more digits. Thus, we print INVALID.
  3. _09090909abcD0 is invalid as the sequence of English alphabetic letters is immediately followed by a number. Thus, we print INVALID.

Solution

import re
import sys
for i in range(int(input())):
    text = sys.stdin.readline()
    pattern = r"^[_.]\d+[a-zA-Z]*_?$"
    print('VALID' if re.match(pattern, text) else 'INVALID')

Comments

Post a Comment