Regexp for a string

Question

I want a regular expression to match all strings like 'T' OR 'T-Th' but NOT values containing only 'Th'

my current regexp is this one:

REGEXP = '[T-Th]'

but it matches all strings 'T' , 'T-Th' and 'Th' which 'Th' is not desirable

This isn't exactly clear. Can you post specific complete examples of strings that should match and examples of those which should be rejected? — Michael Berkowski
– Michael Berkowski, Commented Apr 28, 2014 at 20:15
[T-Th] is the same as [Th] (which matches T or h, not "Th"). — user2864740
– user2864740, Commented Apr 28, 2014 at 20:15
i would like to match strings such as 'T' , 'T-Th' but not strings containing only the value 'Th' — Labrosb
– Labrosb, Commented Apr 28, 2014 at 20:16
You mean literally T or T-Th, rather than words beginning with or containing T or Th as the [] character kind of implies? — Michael Berkowski
– Michael Berkowski, Commented Apr 28, 2014 at 20:18

Sam · Accepted Answer · 2014-04-28 20:18:42Z

1

REGEXP = '(T-Th|T[^h])'

We either match T-Th literally, OR match T that is not followed by anything but an h. In other words: T, T-Th, but not Th.

Regex101

answered Apr 28, 2014 at 20:18

Sam

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Gordon Linoff · Accepted Answer · 2014-04-28 20:18:46Z

1

If I have the logic correct, you want a 'T' in the string and you want a 'T' not followed by 'h':

where col like '%T%' and
      replace(col, 'Th', '') like '%T%'

answered Apr 28, 2014 at 20:18

Gordon Linoff

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elias · Accepted Answer · 2014-04-28 20:37:58Z

0

The - character between brackets is special for regex. It must be escaped when the use is literal. A good alternative for your problem could be this:

REGEXP = '(T-Th|T(?!h))'

edited Apr 28, 2014 at 20:37

answered Apr 28, 2014 at 20:16

elias

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5 Comments

user2864740 Over a year ago

The - is only special inside a character class.

Michael Berkowski Over a year ago

Aside from the escaping not needed, I think this might be what the OP is asking for...

user2864740 Over a year ago

@MichaelBerkowski Wrong information is still wrong and should be corrected before being accepted. Otherwise you ingest poison with an otherwise good bottle of wine.

Michael Berkowski Over a year ago

@user2864740 I don't disagree. My comment was more pointing the fact that the question is still really unclear.

elias Over a year ago

Actually @user2864740 was right, but with backslash works also. Corrected!

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