regexp for blank lines

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

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Re: regexp for blank lines by davido (Cardinal) on Dec 14, 2004 at 05:56 UTC
By blank, do you mean completely empty (except for the final \n)? Or do you mean empty except for whitespace? `# completely empty except for trailing newline... next if $line eq "\n"; # Any amount of whitespace permitted.... next if $line =~ /^\s+$/;` [download] HTH Dave	[reply] [d/l]
Re: regexp for blank lines by slloyd (Hermit) on Dec 14, 2004 at 06:06 UTC
`#strip off carriage returns $line=~s/[\r\n]+$//s; #next if the length of $line is zero next if length($line)==0;` [download]	[reply] [d/l]
Re^2: regexp for blank lines by eyepopslikeamosquito (Archbishop) on Dec 14, 2004 at 08:25 UTC
`$line=~s/[\r\n]+$//s;` To nitpick, the /s modifier above is meaningless; the only effect of /s is to change whether the . (dot) metacharacter matches newline or not. If a pattern does not contain a dot, then /s is meaningless, by definition. See also Re: S And M -- modifiers, that is....	[reply] [d/l]
Re: regexp for blank lines by qq (Hermit) on Dec 14, 2004 at 09:37 UTC
Your regex matches one or more whitespace, so it should match the whitespace between words. Changing it to `/^\s+$/` anchors it at the start and end of the line, which works. Or you can use: `next unless $line =~ /\S/;` "next unless the line contains a non-whitespace character" qq	[reply] [d/l] [select]
Re: regexp for blank lines by prasadbabu (Prior) on Dec 14, 2004 at 06:51 UTC
If you have undef $/ `@arr = split /\n/, $line; map {s/^\n+//;} @arr; $"="\n"; print "@arr"` [download] if you are using while without undef $/, try the following `while ($line = <FILE>) { $line =~ s/^\n+//; }` [download] `the above codes not tested, try it out if it helps you` Prasad	[reply] [d/l] [select]