in reply to Re: loop control
in thread loop control

Here is the actual code: 
$out = "<?xml version="1.0" encoding="utf-8"?>";
@tmp = split /</, $out;
foreach(@tmp) {
  if (substr($_, 0, 1) eq "?") {
    next;
  } elsif (substr($_, 0, 1) eq "!") {
    &more_code;
  }
}

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What this is doing is parsing xml. Note that the leading "<" has already been stripped by the split function. The contents of $tmp here are:

?xml version="1.0" encoding="utf-8"?>

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If I test whether the condition passes or not by simply printing something like "it passed", then I see this.. so I know it's passing the condition.

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Re: Re: Re: loop control
by hotshot (Prior) on May 22, 2002 at 15:08 UTC
    first of all, why not using regexp for parsing the string: 
    if (/^\?/) {
  next;
} elsif (/^\!/) {
  rest of the code ;
}

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    It's much more clear, efficient and fast.
    secondly, you have a problem with the double quotes inside your string, put single quote as outer quotes.
    and third, after fixing the quotes problem it worked for me, I tried it myself.

    Thanks.

    Hotshot
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[d/l]
Re: Re: Re: loop control
by dsheroh (Monsignor) on May 22, 2002 at 15:09 UTC
    Your code as posted (almost) works. After modifying it to 
    #!/usr/bin/perl -w

use strict;

my $out = '<?xml version="1.0" encoding="utf-8"?>';
my @tmp = split /</, $out;
foreach(@tmp) {
  if (substr($_, 0, 1) eq "?") {
    print "conditionA matched - looping!\n";
    next;
  } elsif (substr($_, 0, 1) eq "!") {
    print "conditionB matched\n";
  }
  print "End of loop\n";
}

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    I get the output 
    End of loop
conditionA matched - looping!

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    as expected. (Note that the split is returning a list of two scalars, not just one: the 0 characters before the < and the n characters after it.)

    Side note: That feels a lot like C. Changing your tests to if (/^\?/) and if (/^!/) would feel perlier. Should work either way, though.

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[d/l]
[select]
      OK - the problem was what you mentioned, that split is returning two scalars. The first 0 character result is passing through the conditional check and messing things up - it's not the xml declaration, as I thought. By the way, I tried to abbreviate how the string $out was populated and forgot it had quotes in it, so code as posted would have failed (as you and others noticed). The loop works now - thanks much you guys rock! As for the use of substr instead of regex.. well I was mostly doing it for consistency, because substr works so well for isolating pieces of the xml elements. But, efficiency is more important so I'll change it - thanks for the suggestion :)
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