freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-python/68cae5b538ff798bbd4da005.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
68cae5b538ff798bbd4da005	Challenge 67: Email Validator	29	challenge-67

--description--

Given a string, determine if it is a valid email address using the following constraints:

• It must contain exactly one @ symbol.
• The local part (before the @):
  • Can only contain letters (a-z, A-Z), digits (0-9), dots (.), underscores (_), or hyphens (-).
  • Cannot start or end with a dot.
• The domain part (after the @):
  • Must contain at least one dot.
  • Must end with a dot followed by at least two letters.
• Neither the local or domain part can have two dots in a row.

--hints--

validate("a@b.cd") should return True.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("a@b.cd"), True)`)
}})

validate("hell.-w.rld@example.com") should return True.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("hell.-w.rld@example.com"), True)`)
}})

validate(".b@sh.rc") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate(".b@sh.rc"), False)`)
}})

validate("example@test.c0") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("example@test.c0"), False)`)
}})

validate("freecodecamp.org") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("freecodecamp.org"), False)`)
}})

validate("develop.ment_user@c0D!NG.R.CKS") should return True.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("develop.ment_user@c0D!NG.R.CKS"), True)`)
}})

validate("hello.@wo.rld") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("hello.@wo.rld"), False)`)
}})

validate("hello@world..com") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("hello@world..com"), False)`)
}})

validate("develop..ment_user@c0D!NG.R.CKS") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("develop..ment_user@c0D!NG.R.CKS"), False)`)
}})

validate("git@commit@push.io") should return False.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertIs(validate("git@commit@push.io"), False)`)
}})

--seed--

--seed-contents--

def validate(email):

    return email

--solutions--

import re
def validate(email):
    if '..' in email:
        return False

    parts = email.split('@')
    if len(parts) != 2:
        return False

    local, domain = parts

    if local.startswith('.') or local.endswith('.'):
        return False
    if not re.match(r'^[a-zA-Z0-9._-]+$', local):
        return False

    if '.' not in domain:
        return False

    tld = domain.split('.')[-1]
    if len(tld) < 2 or not tld.isalpha():
        return False

    return True