From: Jeppe Jakobsen <jeppe88@...>
Date: 2006-02-15T03:07:39+09:00
Subject: Scanning a string for decimal numbers

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Thank you for clearing things, up for me, but could you explain what the
last part of the expression Wilson provided me with means?

it's (?=3D[^\d])


2006/2/13, Josef 'Jupp' SCHUGT <jupp@gmx.de>:
>
> Hi!
>
> At Sun, 12 Feb 2006 08:12:47 +0900, Jeppe Jakobsen wrote:
> >
> > Will that expression include both integers and decimal numbers?
>
> [-+]?([1-9]\d*(\,[0-9]+)?)|(0(\,[0-9]+)?)
>
> has two parts:
>
> [-+]?
> ([1-9]\d*(\,[0-9]+)?)|(0(\,[0-9]+)?)
>
>
> The first one is an optional sign. The second one is an alternative
> between to two cases:
>
> [1-9]\d*(\,[0-9]+)?
> 0(\,[0-9]+)?
>
> Let's first consider the first case
>
> [1-9]\d*(\,[0-9]+)?
>
> It has two parts, namely
>
> [1-9]\d*
> (\,[0-9])?
>
> The first part by itself covers all integers larger than zero. The
> overall expression additionally covers all floating point numbers
> larger than 1.
>
> Now the second case
>
> 0(\,[0-9]+)?
>
> This one covers zero and all decimal numbers larger than 0 and smaller
> than 1.
>
> The regex I provided intentionally supports none of
>
> [+-],\d+
> [+-]0+\d+
>
> You may as well use the shorter version
>
> [-+]?(([1-9]\d*(\,\d+)?)|(0(\,\d+)?))
>
> Wait a moment, I am not sure if that is correct. To be on the safe
> side I'd rather use one of these where anything that follows the
> optional sign has been put into another pair of parentheses:
>
> [-+]?(([1-9]\d*(\,[0-9]+)?)|(0(\,[0-9]+)?))
> [-+]?((([1-9]\d*(\,\d+)?)|(0(\,\d+)?)))
>
> I am one of those guys who sometime run out of placeholders when doing
> search and replace in vim (which has nine of them).
>
> Josef 'Jupp' Schugt
> --
> Let the origin be the middle of the earth, p(x,r) be the probability
> density for finding person x at distance r. Make sure that a permanent
> solution of int_0^R p(x,r) dr < 1 exists for R being the instantanous
> value of the distance between earth and mars.
>
>


--
"winners never quit, quitters never win"

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