Shawn H Corey wrote:
Jim Gibson wrote:
On 11/24/09 Tue Nov 24, 2009 4:42 PM, "Orchid Fairy (À¼»¨ÏÉ×Ó)"
<practicalp...@gmail.com> scribbled:
On Wed, Nov 25, 2009 at 8:38 AM, Shawn H Corey <shawnhco...@gmail.com> wrote:
It seems to be picking up an extra empty string after a non-zero length
match.
Thanks John and Shawn.
Yup what let me be confused is that, why there is an additional empty
string there?
You get 4 matches because there are four places in the string 'aXXXb' that
can be matched by 'X*'. Note that a "place" in this case is a position
between characters. The places are:
1. before the a
2. after the a
3. before the b
4. after the b
Funny, I get this on my machine:
$ perl -le '$_="aXXXb"; print "one word is $1 at ", pos while(/(X*)/g);'
one word is at 0
one word is XXX at 4
one word is at 4
one word is at 5
That is:
1. before the a
2. between the a and b
3. before the b
4. after the b
The problem is that the third one should not be there.
Yes it should. Perhaps you are confused because pos() reports the
current position *after* the match has occured? A zero width match has
the same position at the beginning and end however the 'XXX' string has
a different position at the beginning and end. Try using $-[0] for the
beginning of the match and $+[0] for the end of the match.
$ perl -le '$_="aXXXb"; print "one word is $1 at $-[0] to $+[0]" while
/(X*)/g;'
one word is at 0 to 0
one word is XXX at 1 to 4
one word is at 4 to 4
one word is at 5 to 5
John
--
The programmer is fighting against the two most
destructive forces in the universe: entropy and
human stupidity. -- Damian Conway
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