In Python, Is There A Way To Validate A User Input In A Certain Format?

In python, I'm asking the user to input an office code location which needs to be in the format: XX-XXX (where the X's would be letters) How can I ensure that their input follows t

Solution 1:

The standard (and language-agnostic) way of doing that is by using regular expressions:

import re

re.match('^[0-9]{2}-[0-9]{3}$', some_text)

The above example returns True (in fact, a "truthy" return value, but you can pretend it's True) if the text contains 2 digits, a hyphen and 3 other digits. Here is the regex above broken down to its parts:

^     # marks the start of the string
[0-9] # any character between 0 and 9, basically one of 0123456789
{2}   # two times
-     # a hyphen
[0-9] # another character between 0 and 9
{3}   # three times$ # end of string

I suggest you read more about regular expressions (or re, or regex, or regexp, however you want to name it), they're some kind of swiss army knife for a programmer.

Solution 2:

In your case, you can use a regular expression:

import re
whileTrue:
   inp = input() # raw_input in Python 2.xif re.match(r'[a-zA-Z0-9]{2}-[a-zA-Z0-9]{3}$', inp):
       return inp
   print('Invalid office code, please enter again:')

Note that in many other cases, you can simply try converting the input into your internal representation. For example, when the input is a number, the code should look like:

defreadNumber():
    whileTrue:
        try:
          returnint(input()) # raw_input in Python 2.xexcept ValueError:
          pass