Slightly off topic....
How can I write a regex that limits user input to 3 digits in the range of
1-128?
I've been trying \d{1,128} but this allows for a match on more than 3
digits.
Thanks.
11  3326 
Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: How can I write a regex that limits user input to 3 digits in the range of
1-128?
I've been trying \d{1,128} but this allows for a match on more than 3
digits.
Yes - that allows up to 128 digits.
If you want to limit it to 0-128, I suggest you write a simple method
that checks that (e.g. by first checking the length and that all the
characters are digits, and then using Int32.Parse). Is there some
reason you want to use a regular expression?
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Checking the length and then for a max value of 128 is redundant, isn't it?
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: How can I write a regex that limits user input to 3 digits in the range
of 1-128?
I've been trying \d{1,128} but this allows for a match on more than 3
digits.
Yes - that allows up to 128 digits.
If you want to limit it to 0-128, I suggest you write a simple method
that checks that (e.g. by first checking the length and that all the
characters are digits, and then using Int32.Parse). Is there some
reason you want to use a regular expression?
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Daniel Billingsley <db**********@NO.durcon.SPAAMM.com> wrote: Checking the length and then for a max value of 128 is redundant, isn't it?
Only sort of. It's not actually redundant in that it prevents strings
of the form "0123". It's also usful to do as a "first" check before the
more expensive checks (checking that each character is a digit and the
parsing itself).
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
I can see that I didn't make this clear.
I'm trying to limit the user to 3 digits with a possible range of values
from 1-128.
Not 128 digits.
I'm doing it this way because the edit regex is exposed to the user through
configuration choices. So, I'll restrict them to valid regex expressions.
Later, I'll have to use this expression to validate input by another user.
I've come up with this regex,
\b(12[0-8] | 1[0-1][0-9] | [01][0-2][0-8] | [0-9][0-9] | [0-9])\b
This seems to be ok. Is there a better way?
Ron
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: How can I write a regex that limits user input to 3 digits in the range
of 1-128?
I've been trying \d{1,128} but this allows for a match on more than 3
digits.
Yes - that allows up to 128 digits.
If you want to limit it to 0-128, I suggest you write a simple method
that checks that (e.g. by first checking the length and that all the
characters are digits, and then using Int32.Parse). Is there some
reason you want to use a regular expression?
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: I can see that I didn't make this clear.
I'm trying to limit the user to 3 digits with a possible range of values
from 1-128.
Not 128 digits.
Indeed. The problem was that your regular expression *was* allowing 128
digits, because the \d{x,y} bit basically says "I want between x and y
digits inclusive".
I'm doing it this way because the edit regex is exposed to the user through
configuration choices. So, I'll restrict them to valid regex expressions.
Later, I'll have to use this expression to validate input by another user.
I've come up with this regex,
\b(12[0-8] | 1[0-1][0-9] | [01][0-2][0-8] | [0-9][0-9] | [0-9])\b
This seems to be ok. Is there a better way?
Well, you can make it slightly better:
\b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
I *think* that works okay, but to be honest I haven't tried it.
Currently your regular expression isn't terribly clear because the
third "chunk" of it overlaps with the second chunk. (IMO, anyway.)
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Yes, I see the overlap now. Thanks. \b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
What does the ? mean in your regex?
Ron
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: I can see that I didn't make this clear.
I'm trying to limit the user to 3 digits with a possible range of values
from 1-128.
Not 128 digits.
Indeed. The problem was that your regular expression *was* allowing 128
digits, because the \d{x,y} bit basically says "I want between x and y
digits inclusive".
I'm doing it this way because the edit regex is exposed to the user
through configuration choices. So, I'll restrict them to valid regex
expressions. Later, I'll have to use this expression to validate input by another
user.
I've come up with this regex,
\b(12[0-8] | 1[0-1][0-9] | [01][0-2][0-8] | [0-9][0-9] | [0-9])\b
This seems to be ok. Is there a better way?
Well, you can make it slightly better:
\b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
I *think* that works okay, but to be honest I haven't tried it.
Currently your regular expression isn't terribly clear because the
third "chunk" of it overlaps with the second chunk. (IMO, anyway.)
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: Yes, I see the overlap now. Thanks.
\b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
What does the ? mean in your regex?
It's basically "the preceding character is optional".
I really wouldn't start messing around with regular expressions like
this without reading a thorough tutorial on it and having MSDN handy,
personally.
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Agreed!
I use regular expressions about once every 2 years. I still haven't found a
straight forward tutorial that doesn't take days to read through. I even
bought the O'Reilly Regular Expressions book when I was doing some Perl
several years ago. At the time I found it pretty useful. But like most
things, if you don't use it, you lose it.
Do you have any "favorite" sites or books that you like to use for
reference?
Ron
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: Yes, I see the overlap now. Thanks.
\b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
What does the ? mean in your regex?
It's basically "the preceding character is optional".
I really wouldn't start messing around with regular expressions like
this without reading a thorough tutorial on it and having MSDN handy,
personally.
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: Agreed!
I use regular expressions about once every 2 years. I still haven't found a
straight forward tutorial that doesn't take days to read through. I even
bought the O'Reilly Regular Expressions book when I was doing some Perl
several years ago. At the time I found it pretty useful. But like most
things, if you don't use it, you lose it.
Yup.
Do you have any "favorite" sites or books that you like to use for
reference?
I personally just use the MSDN for the most part - but then, I haven't
had to use regular expressions much outside responding to newsgroup
posts :)
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Ron,
A couple of thoughts.
This is the sort of expression that lends itself quite well to brute-force
testing. It's pretty easy for you to throw a whole mess of values at it
(even the whole Int32 range) to see how it behaves.
My general approach is not to do this kind of thing in regex, as it's so
tough to read and debug. It's much easier to do it in code.
If you do, here's my advice:
1) Download my regex tool from here: http://www.gotdotnet.com/Community/U...1-4EE2729D7322
2) Write your regexes like:
string pattern = @"
(
\d | # any single digit number
\d\d | # any two-digit number
1[01]\d # 10d or 11d
12[0-8] # 120 - 128
)
"
You'll need to use RegexOptions.IgnorePatternWhitespace
--
Eric Gunnerson
Visit the C# product team at http://www.csharp.net
Eric's blog is at http://weblogs.asp.net/ericgu/
This posting is provided "AS IS" with no warranties, and confers no rights.
"Ron Rohrssen" <rl******@fightspam.rockwellcollins.com> wrote in message
news:eY*************@TK2MSFTNGP11.phx.gbl... Agreed!
I use regular expressions about once every 2 years. I still haven't found
a straight forward tutorial that doesn't take days to read through. I even
bought the O'Reilly Regular Expressions book when I was doing some Perl
several years ago. At the time I found it pretty useful. But like most
things, if you don't use it, you lose it.
Do you have any "favorite" sites or books that you like to use for
reference?
Ron
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote: Yes, I see the overlap now. Thanks.
> \b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
What does the ? mean in your regex?
It's basically "the preceding character is optional".
I really wouldn't start messing around with regular expressions like
this without reading a thorough tutorial on it and having MSDN handy,
personally.
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
I also found a tool called "The Regex Coach" which was invaluable. It has a
feature to "step" through the evaluation so you can see exactly when things
match or go haywire. It's a standard regex tool and doesn't support all the
features of the .NET implementation.
"Eric Gunnerson [MS]" <er****@online.microsoft.com> wrote in message
news:OJ**************@TK2MSFTNGP12.phx.gbl... Ron,
A couple of thoughts.
This is the sort of expression that lends itself quite well to brute-force
testing. It's pretty easy for you to throw a whole mess of values at it
(even the whole Int32 range) to see how it behaves.
My general approach is not to do this kind of thing in regex, as it's so
tough to read and debug. It's much easier to do it in code.
If you do, here's my advice:
1) Download my regex tool from here:
http://www.gotdotnet.com/Community/U...1-4EE2729D7322
2) Write your regexes like:
string pattern = @"
(
\d | # any single digit number
\d\d | # any two-digit number
1[01]\d # 10d or 11d
12[0-8] # 120 - 128
)
"
You'll need to use RegexOptions.IgnorePatternWhitespace
--
Eric Gunnerson
Visit the C# product team at http://www.csharp.net
Eric's blog is at http://weblogs.asp.net/ericgu/
This posting is provided "AS IS" with no warranties, and confers no
rights. "Ron Rohrssen" <rl******@fightspam.rockwellcollins.com> wrote in message
news:eY*************@TK2MSFTNGP11.phx.gbl... Agreed!
I use regular expressions about once every 2 years. I still haven't
found a straight forward tutorial that doesn't take days to read through. I even
bought the O'Reilly Regular Expressions book when I was doing some Perl
several years ago. At the time I found it pretty useful. But like most
things, if you don't use it, you lose it.
Do you have any "favorite" sites or books that you like to use for
reference?
Ron
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Ron Rohrssen <rl******@fightspam.rockwellcollins.com> wrote:
> Yes, I see the overlap now. Thanks.
>
> > \b(12[0-8] | 1[0-1][0-9] | 0?[0-9]?[0-9])\b
>
> What does the ? mean in your regex?
It's basically "the preceding character is optional".
I really wouldn't start messing around with regular expressions like
this without reading a thorough tutorial on it and having MSDN handy,
personally.
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: Vibha Tripathi |
last post by:
Hi Folks,
I put a Regular Expression question on this list a
couple days ago. I would like to rephrase my question
as below:
In the Python...
|
by: Bradley Plett |
last post by:
I'm hopeless at regular expressions (I just don't use them often
enough to gain/maintain knowledge), but I need one now and am looking
for help. I...
|
by: Lee Kuhn |
last post by:
I am trying the create a regular expression that will essentially match
characters in the middle of a fixed-length string. The string may be any...
|
by: Q. John Chen |
last post by:
I have Vidation Controls
First One: Simple exluce certain special characters:
say no a or b or c in the string:
*
Second One:
I required...
|
by: Ryan |
last post by:
HELLO
I am using the following MICROSOFT SUGGESTED (somewhere on msdn)
regular expression to validate email addresses however I understand
that...
|
by: norton |
last post by:
Hello,
Does any one know how to extact the following text into 4 different
groups(namely Date, Artist, Album and Quality)?
- Artist - Album
...
|
by: Billa |
last post by:
Hi,
I am replaceing a big string using different regular expressions (see
some example at the end of the message). The problem is whenever I
apply...
|
by: Ludwig |
last post by:
Hi,
i'm using the regular expression \b\w to find the beginning of a word,
in my C# application. If the word is 'public', for example, it works....
|
by: Zach |
last post by:
Hello,
Please forgive if this is not the most appropriate newsgroup for this
question. Unfortunately I didn't find a newsgroup specific to...
|
by: Mike |
last post by:
I have a regular expression (^(.+)(?=\s*).*\1 ) that results in
matches. I would like to get what the actual regular expression is.
In other...
|
by: better678 |
last post by:
Question:
Discuss your understanding of the Java platform. Is the statement "Java is interpreted" correct?
Answer:
Java is an object-oriented...
|
by: teenabhardwaj |
last post by:
How would one discover a valid source for learning news, comfort, and help for engineering designs? Covering through piles of books takes a lot of...
|
by: Kemmylinns12 |
last post by:
Blockchain technology has emerged as a transformative force in the business world, offering unprecedented opportunities for innovation and...
|
by: CD Tom |
last post by:
This only shows up in access runtime. When a user select a report from my report menu when they close the report they get a menu I've called Add-ins...
|
by: Naresh1 |
last post by:
What is WebLogic Admin Training?
WebLogic Admin Training is a specialized program designed to equip individuals with the skills and knowledge...
|
by: antdb |
last post by:
Ⅰ. Advantage of AntDB: hyper-convergence + streaming processing engine
In the overall architecture, a new "hyper-convergence" concept was...
|
by: Matthew3360 |
last post by:
Hi there. I have been struggling to find out how to use a variable as my location in my header redirect function.
Here is my code.
...
|
by: Matthew3360 |
last post by:
Hi, I have a python app that i want to be able to get variables from a php page on my webserver. My python app is on my computer. How would I make it...
|
by: WisdomUfot |
last post by:
It's an interesting question you've got about how Gmail hides the HTTP referrer when a link in an email is clicked. While I don't have the specific...
| |
