Re: [Boost-users] regular expression problems

Subject: Re: [Boost-users] regular expression problems
From: Anthony Foglia (AFoglia_at_[hidden])
Date: 2009-04-23 14:04:09

John Maddock wrote:
>> I have a regex that validates a latitude format.
>>
>> These are the restrictions:
>>
>> Must have an N or S as first letter.
>>
>> It can be all values from 0.0 to 90.0
>>
>> My first shot at it confirmed format, but not data constraints:
>> "(N|S)\\d{2}\\.\\d{1,6} <file:///\\d%7b2%7d\d%7b1,6%7d> "
>>
>> But any attempts to limit the constraints caused an exception in 
>> regex. Is
>> there something wrong w/ how I formatted this:
>> "(N|S)(9[0]\\.0{1-6}|[0-8]\\d\\.\\d{1-6}
>> <file:///\\.0%7b1-6%7d|[0-8]\d\d%7b1-6%7d> )"
>>
>>
>>
>> To me, it reads:  1st char must be N|S
>>
>> If second char is 9, the next chars must be 0.0 through 0.000000
>>
>> Else
>>
>> If char is 0-8, then the next just has to be digits [0-9].[0-9]{1-6}
>>
>> Can anyone tell me what I am doing wrong?
> 
> There are no numeric constraints available in the regular expression 
> language, and the {} operator are for constrained repeats with 1{1-6} 
> not being a valid syntax.
> 
> How about something like:
> 
> (N|S)\\d(\\.\\d+|[1-8](\\.\\d+)?|9(\\.0+)?)?

I don't think that will match what he wants.  It will match things like 
"N99.0", which he prohibits.

It looks like the problem is "{1-6}" is invalid syntax.  It should be 
"{1,6}".  In fact, that's what he wrote in his first shot, but not in 
his second.

http://www.boost.org/doc/libs/1_38_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html

-- 
Anthony Foglia