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perl, strip spaces and  double quote character at beginning and at the end of a string

Posted on 2010-08-19
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Last Modified: 2012-08-13
How do I strip spaces and double quote character at beginning and at the end of a string, if the double quote exist?

$string1 = "\"my string1\"";  # => to "my string1"
$string2 = "  \" my string2 \"  "; #=> to " mystring2 "
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Question by:rgbcof
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jeromee earned 63 total points
ID: 33478895
Please try this:
   s/(^\s*")|("\s*$)//g;
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by:YellowShoe
ID: 33479545
Does '\' specify the part where the string starts/ends. If so you could use that as a delimiter as well.

Using your logic - if double quotes and spaces appear at the start and end of strong
$string1 =~ s/^[ "]*//; # delete all spaces and double quotes 0 0r more occurrences
$string1 =~ s/[ "]*$//;

alternately
$string1 = /^[^"]*([^\\]*)\\".*/$1"/;
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Expert Comment

by:wilcoxon
ID: 33479555
This should do it:

$string =~ s{^[\s"]+}{};
$string =~ s{[\s"]+$}{};

Using | as jeromee did above will sometimes work and sometimes not.  For example,

$string =~ s{(?:^[\s"]+)|([\s"]+$)}{};

does not work.
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by:ozo
ozo earned 62 total points
ID: 33479973
s/^\s*"//,s/"\s*$// for $string1,$string2 ;
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by:ozo
ID: 33480017
$string =~ s{(?:^[\s"]+)|([\s"]+$)}{}g; #works, but the g is required, and it is not as fast as s{^[\s"]+}{} and s{[\s"]+$}{}; separately, if you care about that
also, it does
$string2 = "  \" my string2 \"  "; #=> to "mystring2"
unlike the requested
$string2 = "  \" my string2 \"  "; #=> to " mystring2 "
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by:jeromee
ID: 33480100
I think the initial answer I posted:
   s/(^\s*")|("\s*$)//g;
works for both strings.
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Expert Comment

by:ozo
ID: 33480145
Yes, it does work for both strings.
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Expert Comment

by:wilcoxon
ID: 33480712
sigh - yep - I made two mistakes in my comment as ozo pointed out.  I left off the g on the "doesn't work" example (so it does work) and I misread the request so used char classes which are efficient but don't work in this case.

jeromee, yes, your answer worked.  I should have been more clear - I was trying to give a different example that didn't work (and failed at that as well).

Apparently my brain is dead today...
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Author Closing Comment

by:rgbcof
ID: 33480905
You guys are such perl/regex expert.  I am so jealous.
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Expert Comment

by:jeromee
ID: 33480938
If you play with regex regularly it gets easier, and it quickly loses its "crypticness", I promise!

Good luck.
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