Python Regular Expression newline is matched

Question

I want to match a string that has alphanumerics and some special characters but not the newline. But, whenever my string has a newline, it matches the newline character as well. I checked document for some flags but none of them looked relevant.

The following is a sample code in Python 3.6.2 REPL

>>> import re
>>> s = "do_not_match\n"
>>> p = re.compile(r"^[a-zA-Z\+\-\/\*\%\_\>\<=]*$")
>>> p.match(s)
<_sre.SRE_Match object; span=(0, 12), match='do_not_match'>

The expected result is that it shouldn't match as I have newline at the end.

https://regex101.com/r/qyRw5s/1

I am a bit confused on what I am missing here.

Thanks Wiktor. The context might be relevant but it is not a clear duplicate from the question perspective. So, this is why, I couldn't find the answer I was looking for. Also, I was trying to give as much as information as possible. I appreciate the help. — Ömer, Aug 23 '17 at 15:04

score 3 · Accepted Answer · answered Aug 23 '17 at 14:37

3

The problem is that $ matches at the end of the string before the newline (if any).

If you don't want to match the newline at the end, use \Z instead of $ in your regex.

See the re module's documentation:

'$'
Matches the end of the string or just before the newline at the end of the string,

\Z
Matches only at the end of the string.

answered Aug 23 '17 at 14:37

Eugene Yarmash

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Thank you. I read the documentation and it wasn't clear to me. I accept your answer. I am still not sure why regex101 was ignoring this fact though. – Ömer Aug 23 '17 at 14:48
I guess, you need to use the actual enter key there instead of `"\n"`. – Eugene Yarmash Aug 23 '17 at 15:04
so true! thanks for showing me the obvious. :| – Ömer Aug 23 '17 at 15:06

Python Regular Expression newline is matched

1 Answers1