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Why does globally replacing spaces give me the letter "s" instead?Helpful Member!(2) 

Zistrosk (Programmer)
6 Sep 11 23:35
Hi everyone,

I'm running the latest Strawberry Perl, and needed to take a string with multiple spaces and compress them down so there would only be one space in place of many in a row.

Seemed simple to me, I'd just go change all occurrences of two consecutive spaces to a single space, in a while loop, until the condition failed.  However, what I got back was very weird.  Check this out:

#problem compressing double spaces globally

$ma = "     this  test   pattern    has     extra      spaces       in        it.";

print "before: --->" . $ma . "<--- \n";

while ($ma =~ m/\s{2,2}/) { $ma =~ s/\s{2,2}/\s/g;} # compress double spaces down to one each

print "space-compressed: --->" . $ma . "<--- \n";

exit 0;


output:

before: --->     this  test   pattern    has     extra      spaces       in        it.<---

space-compressed: --->ss thisstests patternsshasss extrasssspacessss inssssit.<---


Why were some spaces compressed, and others turned in to the letter "s"?

The first pattern I tried yielded the same result:
while ($ma =~ m/\s\s/) { $ma =~ s/\s\s/\s/g;}


Any ideas?

Thank you very much,

Zistrosk
 
Helpful Member!  prex1 (Programmer)
7 Sep 11 3:12
\s is only for search patterns and stands for whitespace chars, that means space,tab,line feed, carriage return and possibly  some more. In the replacement part  \s  just represents the letter 's': you need to use the real space char there.
Also your regex is incorrect: try this one
s/\s+/ /g;
and this works alone, you don't need to include it in a while loop.
Note also that the regex above will also replace any line feeds in your string. If you don't want this just do
s/ +/ /g;

Franco
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Helpful Member!  Annihilannic (MIS)
7 Sep 11 3:28
If you think about it... \s is a shortcut for multiple white space characters... tab, space and possibly others, in a similar way to \d being a shortcut for any digit.  So how would perl know which one of those characters to use in your replacement string?

Annihilannic
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Zistrosk (Programmer)
7 Sep 11 6:06
Awesome, thanks!  That explains it :)

Appreciate your help.

Zistrosk
1DMF (Programmer)
7 Sep 11 6:53
Have some stars guys!

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you."

"If a shortcut was meant to be easy, it wouldn't be a shortcut, it would be the way!"

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