Remove newline character from start of string

danj35 has asked for the wisdom of the Perl Monks concerning the following question:

Hopefully a nice and easy problem for the monks to solve here:

I have a variable ($string) that contains some script. The script in $string is more than one line long and the content can vary. At the start and the end of the variable are newline characters and I need to remove these. At the moment I've successfully been able to remove the newline character from the end of the string using chomp as so:

chomp $string;
[download]

Does anyone know how to remove the newline character from the start of $string? My first thought is to use regular expressions, although I wouldn't know how to write this, especially when there are likely to be other newline characters between the start and the end.

Many thanks :)

Comment on Remove newline character from start of string Download Code

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Re: Remove newline character from start of string by moritz (Cardinal) on May 10, 2010 at 12:28 UTC
Note that chomp depends on the current value of $/. I assume here that you want to emulate that behaviour. As a regex: `$str =~ s{^\Q$/\E}{};` [download] With substr: `if (substr($str, 0, length($/)) eq $/) { substr($str, 0, length($/), ''; }` [download] Perl 6 - links to (nearly) everything that is Perl 6.	[reply] [d/l] [select]
Re^2: Remove newline character from start of string by Roy Johnson (Monsignor) on May 10, 2010 at 15:29 UTC
Or somewhat oddly, `chomp(substr($str, 0, length($/));` [download] Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re: Remove newline character from start of string by Old_Gray_Bear (Bishop) on May 10, 2010 at 12:42 UTC
Yet another way to do it: `chomp($string); my $rev = reverse($string); chomp($rev); $string = reverse($rev);` [download] Note: Coded Before Coffee; no warranties, no promises. ---- I Go Back to Sleep, Now. OGB	[reply] [d/l]
Re^2: Remove newline character from start of string by danj35 (Sexton) on May 10, 2010 at 13:19 UTC
I like this. Nice and simple. Although thanks to everyone else for providing alternative solutions that also work. Monks rule once more :)	[reply]
Re^2: Remove newline character from start of string by afoken (Chancellor) on May 11, 2010 at 05:21 UTC
Nice, but that works only if `$/ eq reverse($/)`. Otherwise, you also need `local $/=reverse $/` before `chomp($rev)`. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re: Remove newline character from start of string by Ratazong (Monsignor) on May 10, 2010 at 12:20 UTC
Try this: `my $str = "\nxyz\nabc\n"; $str =~ s/^\n//;` [download] HTH, Rata	[reply] [d/l]
Re: Remove newline character from start of string by Marshall (Canon) on May 10, 2010 at 13:05 UTC
To remove all new lines within $line: $line =~ tr/\n//d; $line =~ s/^\n//; #remove leading one $line =~ s/\n$//; #remove last one or better use chomp($line)	[reply]


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