Regex pattern for matching "-" character but only if there are other word characters present

user_19315928 0
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I have a set of entries for matching. One pattern, that I have already written, matches strings that consist of "-" only, e.g.:

----
---
--------

The regex code for matching these is

r"^[-]+$"

Now I need to match strings that contain "-" character, but only if there are other word characters in the string, e.g.:

---vsgvrf-sgwfwrgfs---
-----hwvchwbfk
bfcbewubf------
-efefe-ege-
-gdiwen

Etc. I have tried next patterns, but they do not work and skip some of the string:

r"(\w[^-])+-+(\w[^-])*"
r"\w[^-]+-+\w[^-]+|-+\w[^-]+|\w[^-]+-+"

Could somebody help me here?

python regex
4 Answers

Use this regex (word char before or after a dash):

r'(-\w|\w-)'
user_9676210

If hyphen and \w both are required, how about:

^(?:-+\w|\w+-)[\w-]*$

See this demo at regex101

If just \w is required with an optional amount of hyphens and word characters:

^-*\w[-\w]*$

Another demo at regex101 (to me your question reads like this would suffice)

user_55279850

You can do it with ((?:\w+-+|-+\w+)+\w*-*).

import re
m = re.compile(r'((?:\w+-+|-+\w+)+\w*-*)')
lines = ['-Before', '-Before-Middle', 'Middle-After-', 'After-', '--All--Three--', 'No Match', '-', '--', '---']
for line in lines:
    if m.match(line):
        print(m.match(line).groups())

Output:

('-Before',)
('-Before-Middle',)
('Middle-After-',)
('After-',)
('--All--Three--',)
user_19913970

Another option with a negative lookahead asserting not only word characters:

^(?!\w+$)-*\w[\w-]*$

Regex demo

user_54249880
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