in reply to substituted text is being interpreted

mmh.
this runs as expected: 
$somethingelse="AA";
$var = 'BB';
$_ = 'beforeBBafter';
s@$var@$somethingelse@;
print; #prints "beforeAAafter"

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but this does not: 
$somethingelse="AA";
$var = '<a href="somefilename(x)withanumberedhash.htm#666">';
$_ = 'before<a href="somefilename(x)withanumberedhash.htm#666">after';
s@$var@$somethingelse@;
print;

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and that is because of the braces() which are regex special chars. if you 
$somethingelse="AA";
$var = '<a href="somefilename\(x\)withanumberedhash.htm#666">';
$_ = 'before<a href="somefilename(x)withanumberedhash.htm#666">after';
s@$var@$somethingelse@;
print;

[download]
it works fine.

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Re^2: substituted text is being interpreted
by wolfger (Deacon) on Jan 06, 2005 at 15:14 UTC
    Interesting. I thought using single quotes meant you didn't have to escape special characters. Is this because the regex grabs the single quoted text and then interprets it as a normal (double-quoted) expression?

    --
    Linux, sci-fi, and Nat Torkington, all at Penguicon 3.0
    perl -e 'print(map(chr,(0x4a,0x41,0x50,0x48,0xa)))'
[reply]

      It's a bit subtler than that.

      When you write string literals, single-quoting them make them contain exactly the characters you typed, while double-quoting them activates the interpolation mechanism.

      On the other hand, when you use a string as a regular expression, it gets interpreted by the regex engine.

      For example:

      $literal='abc@array$';
@array=(1,2,3);
$interpolated="abc@array\$";

print 'literal: ',$literal,"\n";
print 'interp.: ',$interpolated,"\n";

if ($literal =~ /$literal/) {
  print "literal matches itself\n"
} else {
  print "literal doesn't match itself\n"
}

$literal2='abc@array';
if ($literal2 =~ /$literal2/) {
  print "literal2 matches itself\n"
} else {
  print "literal2 doesn't match itself\n"
}

if ($literal2 =~ /$literal/) {
  print "literal2 matches literal\n"
} else {
  print "literal2 doesn't match literal\n"
}

      [download]

      This prints:

      literal: abc@array$
interp.: abc1 2 3$
literal doesn't match itself
literal2 matches itself
literal2 matches literal

      [download]

      The first two lines are hopefully obvious. As for the others:

      • $literal does not match itself because, seen as a regexp, it requires the string it matches to end with a y (the $ is interpreted by the regexp engine)
      • $literal2 does match itself. This is to confirm that the regexp is not "double-quote-interpolated-expanded-whathaveyou": the @ is still a single character.
      • $literal2 matches $literal because it does end in a y.
      OK, for the pedants: the string between the // is interpolated, but its contents are not further expanded. I felt that this was more noise than signal, in this case.
      -- 
        dakkar - Mobilis in mobile

      Most of my code is tested...

      Perl is strongly typed, it just has very few types (Dan)

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