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Old 03-23-2011, 02:13 AM   #1
smeezekitty
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Regular expression help


I need a regular expression that would match:
Code:
-5
-39
9
17
but not match
Code:
3-4
 
Old 03-23-2011, 04:19 AM   #2
Disillusionist
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grep "^[-0-9][0-9]*$"

Last edited by Disillusionist; 03-23-2011 at 04:19 AM. Reason: Forgot the *
 
Old 03-25-2011, 07:18 AM   #3
kaz2100
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Hya

How about ?
Code:
grep -e '-5\|-39\|9\|17'
Happy Penguins??
 
Old 03-27-2011, 08:13 AM   #4
Disillusionist
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I think the requirement was to match any integer number (plus or minus)

I believe the examples were just that, examples or sample data.
 
Old 03-27-2011, 08:23 AM   #5
carltm
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Quote:
Originally Posted by kaz2100 View Post
How about ?
Code:
grep -e '-5\|-39\|9\|17'
Happy Penguins??
Quite happy after a good laugh.

I like that you found a humorous way to show that we didn't
have a good definition of the problem.
 
Old 03-27-2011, 08:29 AM   #6
carltm
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Smeezekitty, will Disallusionist's solution work for you?

You don't mention what program you are using or in what
context. A regex that works in grep might give different
results when used in egrep or sed.
 
Old 03-27-2011, 09:17 AM   #7
CroMagnon
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Disillusionist's expression would also match "-" on its own, which might not be appropriate.

I would use
Code:
^-?[0-9]+$
or
Code:
^-\?[0-9]\+$
for grep's simple regular expressions. Most regex implementations should support an expression that simple.
 
Old 03-27-2011, 08:57 PM   #8
kurumi
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I see that you are just checking for positive or negative numbers? In that case, use < or > operator eg >0 , or <0. No need to use regular expression.
 
  


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