I'm trying to take a regular expression as an argument to my python program (which is a string naturally) and simply match it against another string.
Let's say I run it as
python program.py 'Hi.there'
I'd like to be able to then take that input (call it input) and say whether or not it matches 'HiTthere' (it should).
How should I do this? I'm inexperienced at regex.
From my understanding, you're looking for something like:
import sys, re
regex = sys.argv[1]
someOtherString = 'hi there'
found = re.search(regex, someOtherString)
print('ok' if found else 'nope')
Run this program with an expression as a first argument:
> python test.py hi.th
ok
> python test.py blah
nope
Unlike, say, javascript, python regexes are simple strings, so you can directly use sys.argv[1] as an argument to re.search.
Python 3 syntax (Python 2, use print xxx instead of print(xxx)):
import re
if re.match(r'^Hi.there$', 'HiTthere'): # returns a "match" object or None
print("matches")
else:
print("no match")
Note that I'm using the anchors ^ and $ to guarantee that the match spans the entire input. ^ matches the start of the string and $ matches the end of the string.
See the documentation for much more detail.
$ anchor since re.match starts at the start of the string by default.
^/$ as a pair to be more explicit, but you can skip ^.'HiTthere' with sys.argv[1] (with proper import of course).re.search and leave off the anchors (^/$).