Question

•Write a regular expression for both a zip code and a phone number in python.

Answer 1

1> We need to validate a ZIP code (U.S. postal code), allowing both the five-digit and nine-digit (called ZIP+4) formats. The regex should match 12345 and 12345-6789, but not 1234, 123456, 123456789, or 1234-56789.

Regular expression:

^[0-9]{5}(?:-[0-9]{4})?$

=> To understand the regular expression:

^           # Assert position at the beginning of the string.
[0-9]{5}    # Match a digit, exactly five times.
(?:         # Group but don't capture:
  -         #   Match a literal "-".
  [0-9]{4}  #   Match a digit, exactly four times.
)           # End the noncapturing group.
  ?         #   Make the group optional.
$           # Assert position at the end of the string.

2> Let say, you want to validate & format north americans phone numbers, then you need to determine whether a user entered a North American phone number, including the local area code, in a common format. These formats include 1234567890, 123-456-7890, 123.456.7890, 123 456 7890, (123) 456 7890, and all related combinations. If the phone number is valid, you want to convert it to your standard format, (123) 456-7890, so that your phone number records are consistent.​

^\(?([0-9]{3})\)?[-.●]?([0-9]{3})[-.●]?([0-9]{4})$

^        # Assert position at the beginning of the string.
\(       # Match a literal "("
  ?      #   between zero and one time.
(        # Capture the enclosed match to backreference 1:
  [0-9]  #   Match a digit
    {3}  #     exactly three times.
)        # End capturing group 1.
\)       # Match a literal ")"
  ?      #   between zero and one time.
[-. ]    # Match one hyphen, dot, or space
  ?      #   between zero and one time.
⋯       # [Match the remaining digits and separator.]
$        # Assert position at the end of the string.

3> if you need to validate international phone numbers. The numbers should start with a plus sign, followed by the country code and national number.

^\+(?:[0-9]●?){6,14}[0-9]$

^         # Assert position at the beginning of the string.
\+        # Match a literal "+" character.
(?:       # Group but don't capture:
  [0-9]   #   Match a digit.
  \x20    #   Match a space character
    ?     #     between zero and one time.
)         # End the noncapturing group.
  {6,14}  #   Repeat the group between 6 and 14 times.
[0-9]     # Match a digit.
$         # Assert position at the end of the string.