Problem Statement:
We are given a string, we need to check whether the string is a valid username or not. To be a valid username, the string should satisfy the following conditions:
- The string should only contain letters, numbers, or underscore(s).
- It should not start with a number.
- It should not end with an underscore.
- Its length should be greater than equal to 4 and less than equal to 25.
Code for Validation in Python:
def check_username(s): alphabets = list('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ') numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] if (type(s[0]) != str): return 'Invalid Username1' if (len(s)<4): return 'Invalid Username2' if (len(s)>25): return 'Invalid Username3' if (s[-1] == '_'): return 'Invalid Username4' for i in s: if (i in alphabets) or (i == '_') or (i in numbers): continue return 'Invalid Username5' return 'Valid Username' t = int(input('Enter number of test cases: ')) for i in range(t): s = input('\nEnter username: ') s = list(s) for i in range(len(s)): try: s[i] = int(s[i]) except: continue print(check_username(s), '\n')
Output:
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