Regular expression help

smeezekitty · 03-23-2011, 01:13 AM

I need a regular expression that would match:

Code:

but not match

Code:

3-4

Disillusionist · 03-23-2011, 03:19 AM

grep "^[-0-9][0-9]*$"

kaz2100 · 03-25-2011, 06:18 AM

Hya

How about ?

Code:

grep -e '-5\|-39\|9\|17'

Happy Penguins??

Disillusionist · 03-27-2011, 07:13 AM

I think the requirement was to match any integer number (plus or minus)

I believe the examples were just that, examples or sample data.

carltm · 03-27-2011, 07:23 AM

Quote:

Originally Posted by kaz2100

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.

carltm · 03-27-2011, 07:29 AM

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.

CroMagnon · 03-27-2011, 08:17 AM

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.

kurumi · 03-27-2011, 07:57 PM

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.