Need help making email verifications with the variable 'pattern' and making it so that it loops if it doesn't contain whatever is within the pattern. Required to use re.search. I tried a couple of things for the last hour and this is where I'm kind of lost.

import re
pattern = '[a-zA-Z0-9]'   '[a-zA-Z0-9]' '@[a-zA-Z]' '(.com/.edu/.net)'
user_input = input('Enter Your Email:')
while user_input is not pattern:
    if (re.search(pattern,user_input)):
        print(re.seach(pattern,user_input))
        print('Valid Email:'  user_input)
    else:
        print(re.search(pattern,user_input))
        print('Invalid Email:'  user_input)
        user_input = input('Enter Your Email:')```

CodePudding user response：

I made a slight modification to your pattern and to your code.

import re
pattern = '[a-zA-Z0-9] @[a-zA-Z] (.com|.edu|.net)'
while True:
  user_input = input('Enter Your Email:')
  if (re.search(pattern,user_input)):
      print(re.search(pattern,user_input))
      print('Valid Email:'  user_input)
      break
  else:
      print(re.search(pattern,user_input))
      print('Invalid Email:'  user_input)
     

Here's an example run:

Enter Your Email:fred
None
Invalid Email:fred
Enter Your Email:[email protected]
<re.Match object; span=(0, 11), match='[email protected]'>
Valid Email:[email protected]

CodePudding user response：

The code is great, but the pattern lacks a bit of functionality. In fact for e-mail addresses, it misses the dash - and the underscore _. Luckily, you can just say to match \w. It is the same as if you would have specified [a-zA-Z0-9_]. (it still misses the dash though, so your approach is good but too short.) Anyway, there are a few further things that an address should meet.

1. it must start with a alphabetic character
2. While theoretically, the address could be composed of a single character at the start and only to after the @ sign, and be almost infinitely long, it is highly unlikely

I suggest the pattern '[a-zA-Z] [a-zA-Z0-9_\-]{0,42}@[a-zA-Z]{2,42}'\.((com)|(edu)|(net))\b?'

Limiting the number of characters with '{m,n}' lets you ensure that you won't have an overflow error when storing the address. Well and addresses shorter than '[email protected]' simply don't exist as at least two characters are required.

Lastly, the or-operator applies only to the immediate adjoin characters, so you need to group the mail extensions: ((com)|(edu)|(net))

import re
pattern = '[a-zA-Z] [a-zA-Z0-9_\-]{0,42}@[a-zA-Z]{2,42}'\.((com)|(edu)|(net))\b?'
while True:
  user_input = input('Enter Your Email:')
  if re.match(pattern, user_input):
      print(re.search(pattern,user_input))
      print('Valid Email:'  user_input)
      break
  else:
      print(re.match(pattern,user_input))
      print('Invalid Email:'  user_input)

I think, it is better if you use re.match() as it matches the string right from the start. Usually one doesn't like if you end up with [email protected] to be a valid address (because re.search() would find the valid string [email protected]. With the same argumentation, you should add a \b to the end of the pattern