Cine has asked for the wisdom of the Perl Monks concerning the following question:

Does anyone have any clue as to why these two pieces of code does not behave the same? 
  my $head = $mail->head();

  if (!$head->get('From') || !$head->get('To') ||
      $head->get('From') eq "<>" || $head->get('To') eq "<>" ) {goto N
+EXT;}

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and 
  my $head = $mail->head();

  if (!$head->get('From') || !$head->get('To') ||
      $head->get('From') =~ /^<>$/ || $head->get('To') =~ /^<>$/) {got
+o NEXT;}

[download]


T I M T O W T D I

Replies are listed 'Best First'.
Re: Weird eq behaviour
by choocroot (Friar) on Jul 25, 2002 at 12:49 UTC
    Because of a trailing \n char ???

    From perlop, it says :

    Binary "eq" returns true if the left argument is
    stringwise equal to the right argument.

    So the string should be exactly the same, byte by byte.

    Try this : 
    perl -e 'print "Ok\n" if( "foo\n" eq "foo" )'

    [download]
    this one print nothing ... 
    perl -e 'print "Ok\n" if( "foo\n" =~ /^foo$/ )'

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    but this one print Ok !
[reply]
[d/l]
[select]
      Offcourse :(
      I didnt think of this because I tried to print the line after a s/./ord($&)." "/ge, but that doesnt change the newline either... ARG ;)

      T I M T O W T D I
[reply]
[d/l]
        use the s modifier on the regexp to catch newline chars : 
        s   Treat string as single line.  That is, change "." to
    match any character whatsoever, even a newline, which
    normally it would not match.

        [download]
        s/./ord($&)." "/ges
[reply]
[d/l]
Re: Weird eq behaviour
by jmcnamara (Monsignor) on Jul 25, 2002 at 12:48 UTC

    There shouldn't be any difference in this case. The operators eq and =~ have different precendence but they are both higher than || 
    my $from = '<>';
my $to   = '<>';

if (!$from || !$to || $from eq "<>"   || $to eq "<>"  ) {print "Ok 1\n
+"}
if (!$from || !$to || $from =~ /^<>$/ || $to =~ /^<>$/) {print "Ok 2\n
+"}

__END__
Prints:
Ok 1
Ok 2

    [download]

    --
    John.

[reply]
[d/l]
      Well I would agree with you except for the simple fact that I had an email, for which I had to add the regexp aswell to my script because it die in the next lines trying to parse "<>"...

      T I M T O W T D I
[reply]

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