Regex letter order matching

[cspctec]

I need to create a regex that matches a string like this:

odm_trs84t1cb1

But does not match this (only match when 'cb' is together):

odm_trs84t1b01

So far, I have created this regex:

[A-Za-z_-]+\d{1,3}[lt]\d[bcfmrtw]+\d+

But it matches both strings. I have been investigating positive lookbehind, but I haven't gotten it to work on regexpal.com

I would appreciate some help

Thanks for the help everyone... this regex seems to work:

[A-Za-z_-]+\d{1,3}[lt]\d(cb|m)\d+

[hippo]

/[A-Za-z_-]+\d{1,3}[lt]\d[bcfmrtw]{2,}\d+/

Will match the "cb" case but not the "b". Do you see why?

[Anonymous Monk]

Like this

m{
$before # whatever
cb
$after  # whatever
}msx;

where $before and $after are whatever prefix/suffix you need

Or did you want something else?

[Anonymous Monk]

that can work if you do TWO match operations

1) match pattern to reject (the one with cb) 2) match pattern to accept (same exact pattern except no "cb" literal

Or look ahead

$ perl -Mre=debug -le " $_ = q{this TON that}; m{this \s+ (?!NOT)\w+ \
+s+that}msgx; "
Compiling REx "this \s+ (?!NOT)\w+ \s+that"
Final program:
   1: EXACT <this> (3)
   3: PLUS (5)
   4:   SPACE (0)
   5: UNLESSM[0] (11)
   7:   EXACT <NOT> (9)
   9:   SUCCEED (0)
  10: TAIL (11)
  11: PLUS (13)
  12:   ALNUM (0)
  13: PLUS (15)
  14:   SPACE (0)
  15: EXACT <that> (17)
  17: END (0)
anchored "this" at 0 floating "that" at 7..2147483647 (checking floati
+ng) minlen 11
Guessing start of match in sv for REx "this \s+ (?!NOT)\w+ \s+that" ag
+ainst "this TON that"
Found floating substr "that" at offset 9...
Found anchored substr "this" at offset 0...
Guessed: match at offset 0
Matching REx "this \s+ (?!NOT)\w+ \s+that" against "this TON that"
   0 <> <this TON t>         |  1:EXACT <this>(3)
   4 <this> < TON that>      |  3:PLUS(5)
                                  SPACE can match 1 times out of 21474
+83647...
   5 <this > <TON that>      |  5:  UNLESSM[0](11)
   5 <this > <TON that>      |  7:    EXACT <NOT>(9)
                                      failed...
   5 <this > <TON that>      | 11:  PLUS(13)
                                    ALNUM can match 3 times out of 214
+7483647...
   8 <his TON> < that>       | 13:    PLUS(15)
                                      SPACE can match 1 times out of 2
[phone]...
   9 <his TON > <that>       | 15:      EXACT <that>(17)
  13 <his TON that> <>       | 17:      END(0)
Match successful!
Freeing REx: "this \s+ (?!NOT)\w+ \s+that"

[mtmcc]

If you just want to distinguish those two strings, then see above.

If there might be other strings involved (and there usually are), then you might want to think a bit further.

In either case, have you read this?

I'm fairly sure it's all in there.