Regex help

[Chris Lervag]

Hi
I want to test a string for three properties:
1) It is exactly 9 characters long.
2) Character number 5 is a comma (',').
3) The other characters are either numbers 0-9 or letters a-f.

I have been able to do this by a combination of strings methods for 1)
and 2), and using a regex match on the string (stripped of the comma)
with the following code:
myString =~ /([^a-f0-9])/

If possible I would like to simplify this by using a more advanced regex
match to check all three properties at one time. If this is possible,
perhaps one of you regex wizards out there could show me how?

Best regards,
Chris

 

[Stefano Crocco]

|Hi
|I want to test a string for three properties:
|1) It is exactly 9 characters long.
|2) Character number 5 is a comma (',').
|3) The other characters are either numbers 0-9 or letters a-f.
|
|I have been able to do this by a combination of strings methods for 1)
|and 2), and using a regex match on the string (stripped of the comma)
|with the following code:
|myString =~ /([^a-f0-9])/
|
|If possible I would like to simplify this by using a more advanced regex
|match to check all three properties at one time. If this is possible,
|perhaps one of you regex wizards out there could show me how?
|
|Best regards,
|Chris

You could do this with a regexp which matches the following:
* the beginning of the string
* four characters of type a-f or digits
* a comma
* four characters of type a-f or digits
* the end of the string

The regexp is:
/^[a-f\d]{4},[a-f\d]{4}$/

Note that your string can contain newlines, you must replace ^ and $ with \A
and \Z respectively.

I hope this helps

Stefano

 

[Jesús Gabriel y Galán]

Hi
I want to test a string for three properties:
1) It is exactly 9 characters long.
2) Character number 5 is a comma (',').
3) The other characters are either numbers 0-9 or letters a-f.

I have been able to do this by a combination of strings methods for 1)
and 2), and using a regex match on the string (stripped of the comma)
with the following code:
myString =~ /([^a-f0-9])/

If possible I would like to simplify this by using a more advanced regex
match to check all three properties at one time. If this is possible,
perhaps one of you regex wizards out there could show me how?

irb(main):006:0> re = /\A[a-f0-9]{4},[a-f0-9]{4}\z/
=> /\A[a-f0-9]{4},[a-f0-9]{4}\z/
irb(main):007:0> "abcd,4f2ddf" =~ re
=> nil
irb(main):008:0> "abcd,4f32" =~ re
=> 0

Hope this helps,

Jesus.

 

[Robert Klemme]

|Hi
|I want to test a string for three properties:
|1) It is exactly 9 characters long.
|2) Character number 5 is a comma (',').
|3) The other characters are either numbers 0-9 or letters a-f.
|
|I have been able to do this by a combination of strings methods for 1)
|and 2), and using a regex match on the string (stripped of the comma)
|with the following code:
|myString =3D~ /([^a-f0-9])/
|
|If possible I would like to simplify this by using a more advanced rege= x
|match to check all three properties at one time. If this is possible,
|perhaps one of you regex wizards out there could show me how?
|
|Best regards,
|Chris

You could do this with a regexp which matches the following:
* the beginning of the string
* four characters of type a-f or digits
* a comma
* four characters of type a-f or digits
* the end of the string

The regexp is:
=A0/^[a-f\d]{4},[a-f\d]{4}$/

Note that your string can contain newlines, you must replace ^ and $ with= \A
and \Z respectively.

I believe this should rather be \z because \Z allows for a follwing
newline. So that would be

/\A[a-f\d]{4},[a-f\d]{4}\z/

see http://www.geocities.jp/kosako3/oniguruma/doc/RE.txt

Kind regards

robert

--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

 

[Stefano Crocco]

|> You could do this with a regexp which matches the following:
|> * the beginning of the string
|> * four characters of type a-f or digits
|> * a comma
|> * four characters of type a-f or digits
|> * the end of the string
|>
|> The regexp is:
|> /^[a-f\d]{4},[a-f\d]{4}$/
|>
|> Note that your string can contain newlines, you must replace ^ and $
|> with \A and \Z respectively.
|
|I believe this should rather be \z because \Z allows for a follwing
|newline. So that would be
|
|/\A[a-f\d]{4},[a-f\d]{4}\z/

You're right.

Stefano

 

[Phrogz]

/\A[a-f\d]{4},[a-f\d]{4}\z/

Slightly more terse:
/\A\h{4},\h{4}\z/
....where \h is a hexadecimal character [0-9a-fA-F] (assuming upper-
case a-f is fine).

 

[Chris Lervag]

Slightly more terse:
/\A\h{4},\h{4}\z/
...where \h is a hexadecimal character [0-9a-fA-F] (assuming upper-
case a-f is fine).

Alright, thanks guys for excellent insight and help! I especially like
this last suggestion which is both compact and easy to comprehend.