# Regex help partial code
**URL:** https://rubytalk.org/t/regex-help-partial-code/43748
**Category:** ruby-talk
**Created:** [13 January 2008 21:30 UTC](https://rubytalk.org/t/regex-help-partial-code/43748 "2008-01-13T21:30:02Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Junkone](https://rubytalk.org/u/Junkone)
#### Post date: [13 January 2008 21:30 UTC](https://rubytalk.org/t/regex-help-partial-code/43748/1 "2008-01-13T21:30:02Z")
Hello
I have with great effort started on teh regex implemention and am
stuck at one point.
here is my code
(add)\s+\S+\s+[i|s|f]\s+[pei]?\s+
The string is as follows and the tokens are equavalent to
1 token=Add
2 token=any text
3. token=one of the following i or s or f
4.token= 0 or 1 of the following characters [p e i]
I am stuck at the 4th token. i thought ? after the token will give
the 0 or 1 option.
pl correct me if i made a error
seede
---
### Author:  [@John\_Carter](https://rubytalk.org/u/John_Carter)
#### Post date: [13 January 2008 22:49 UTC](https://rubytalk.org/t/regex-help-partial-code/43748/2 "2008-01-13T22:49:51Z")
> Hello
> I have with great effort started on teh regex implemention and am
> stuck at one point.
> here is my code
> (add)\s+\S+\s+[i|s|f]\s+[pei]?\s+
>
> The string is as follows and the tokens are equavalent to
> 1 token=Add
Unless you use the i modifier, ruby regexps are case sensitive. So
/add/ won't match /Add/, but /add/i will.
> 2 token=any text
> 3. token=one of the following i or s or f
You want /[isf]/ /[i|s|f]/ is probably equivalent to /[isf|]/
> 4.token= 0 or 1 of the following characters [p e i]
/[pei]?/
> I am stuck at the 4th token. i thought ? after the token will give
> the 0 or 1 option.
It does.
> pl correct me if i made a error
Show the exact regexp and the string it failed on.
John Carter Phone : (64)(3) 358 6639
Tait Electronics Fax : (64)(3) 359 4632
PO Box 1645 Christchurch Email : john.carter@tait.co.nz
New Zealand
> **···**
>
> On Mon, 14 Jan 2008, Junkone wrote:
---
### Author:  [@Junkone](https://rubytalk.org/u/Junkone)
#### Post date: [13 January 2008 23:45 UTC](https://rubytalk.org/t/regex-help-partial-code/43748/3 "2008-01-13T23:45:04Z")
irb(main):046:0\> a=Regexp.new('(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s
+',true)
=\> /(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s+/i
irb(main):047:0\> a =~("Add comp i pe")
=\> nil
I dont get match at 4th token
> **···**
>
> On Jan 13, 4:25 pm, Junkone \ wrote:
>
> > Hello
> > I have with great effort started on teh regex implemention and am
> > stuck at one point.
> > here is my code
> > (add)\s+\S+\s+[i|s|f]\s+[pei]?\s+
> >
> > The string is as follows and the tokens are equavalent to
> > 1 token=Add
> > 2 token=any text
> > 3. token=one of the following i or s or f
> > 4.token= 0 or 1 of the following characters [p e i]
> >
> > I am stuck at the 4th token. i thought ? after the token will give
> > the 0 or 1 option.
> > pl correct me if i made a error
> >
> > seede
---
### Author:  [@John\_Carter](https://rubytalk.org/u/John_Carter)
#### Post date: [14 January 2008 00:56 UTC](https://rubytalk.org/t/regex-help-partial-code/43748/4 "2008-01-14T00:56:55Z")
irb
irb(main):002:0\> /(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s+/i =~ "Add comp i pe"
=\> nil
irb(main):003:0\> /(add)\s+(\S+)\s+([i|s|f])\s+([pei])?/i =~ "Add comp i pe"
=\> 0
The last \s+ insists on matching one or more whitespace chars.
Here is a general recipe for solving this class of problems....
Set up a simple test like I have above...
Delete elements out of the regex until it matches.
The problem was the last one you deleted.
John Carter Phone : (64)(3) 358 6639
Tait Electronics Fax : (64)(3) 359 4632
PO Box 1645 Christchurch Email : john.carter@tait.co.nz
New Zealand
> **···**
>
> On Mon, 14 Jan 2008, Junkone wrote:
>
> > irb(main):046:0\> a=Regexp.new('(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s
> > +',true)
> > =\> /(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s+/i
> > irb(main):047:0\> a =~("Add comp i pe")
> > =\> nil
> >
> > I dont get match at 4th token
---
### Author:  [@yermej](https://rubytalk.org/u/yermej)
#### Post date: [14 January 2008 06:25 UTC](https://rubytalk.org/t/regex-help-partial-code/43748/5 "2008-01-14T06:25:11Z")
There are a few problems here, I think.
Regexp.new('(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s+',true)
As written, the second token can't have whitespace. Is that what you
intended?
You want ([isf]) for your third token. That will match a single
instance of one of the three characters.
Also, I'm not clear on what you want for the fourth token. Do you want
0 or 1 of [pei] or 0 or 1 of \*each\* of [pei] - which of these are
valid for the fourth token: e or pe.
You should also end the regex with \s\* unless there's always going to
be whitespace. You're currently checking for one or more whitespace
characters at the end, but your test didn't have any.
Assuming you do allow 0 or 1 of each of [pei] for the fourth token and
0 or more whitespace characters at the end, I would use:
r = /(add)\s+(\S+)\s+([isf])\s+(p?e?i?)\s\*/i
Though, if there can't be whitespace in any of the tokens, you might
want to use split rather than a regex. The regex above can only get
the fourth token right if the letters are in order - p will match, ei
will match, ip will not. Split wouldn't have that problem. There may
be a regex way around that, but I can't think of it at the moment.
"Add comp i ep".scan r # =\> [["Add", "comp", "i", "e"]]
"Add comp i ep".split # =\> ["Add", "comp", "i", "ep"]
> **···**
>
> On Jan 13, 5:41 pm, Junkone \ wrote:
>
> > On Jan 13, 4:25 pm, Junkone \ wrote:
> >
> > \> Hello
> > \> I have with great effort started on teh regex implemention and am
> > \> stuck at one point.
> > \> here is my code
> > \> (add)\s+\S+\s+[i|s|f]\s+[pei]?\s+
> >
> > \> The string is as follows and the tokens are equavalent to
> > \> 1 token=Add
> > \> 2 token=any text
> > \> 3. token=one of the following i or s or f
> > \> 4.token= 0 or 1 of the following characters [p e i]
> >
> > \> I am stuck at the 4th token. i thought ? after the token will give
> > \> the 0 or 1 option.
> > \> pl correct me if i made a error
> >
> > \> seede
> >
> > irb(main):046:0\> a=Regexp.new('(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s
> > +',true)
> > =\> /(add)\s+(\S+)\s+([i|s|f])\s+([pei])?\s+/i
> > irb(main):047:0\> a =~("Add comp i pe")
> > =\> nil
> >
> > I dont get match at 4th token