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Removing blank columns from a file
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Text::Trim(3pm) User Contributed Perl Documentation Text::Trim(3pm) NAME
Text::Trim - remove leading and/or trailing whitespace from strings VERSION
version 1.02 SYNOPSIS
use Text::Trim; $text = " important data "; $data = trim $text; # now $data contains "important data" and $text is unchanged # or: trim $text; # work in-place, $text now contains "important data" @lines = <STDIN>; rtrim @lines; # remove trailing whitespace from all lines # Alternatively: @lines = rtrim <STDIN>; # Or even: while (<STDIN>) { trim; # Change $_ in place # ... } DESCRIPTION
This module provides functions for removing leading and/or trailing whitespace from strings. It is basically a wrapper around some simple regexes with a flexible context-based interface. EXPORTS
All functions are exported by default. CONTEXT HANDLING
void context Functions called in void context change their arguments in-place trim(@strings); # All strings in @strings are trimmed in-place ltrim($text); # remove leading whitespace on $text rtrim; # remove trailing whitespace on $_ No changes are made to arguments in non-void contexts. list context Values passed in are changed and returned without affecting the originals. @result = trim(@strings); # @strings is unchanged @result = rtrim; # @result contains rtrimmed $_ ($result) = ltrim(@strings); # like $result = ltrim($strings[0]); scalar context As list context but multiple arguments are stringified before being returned. Single arguments are unaffected. This means that under these circumstances, the value of $" ($LIST_SEPARATOR) is used to join the values. If you don't want this, make sure you only use single arguments when calling in scalar context. @strings = (" hello ", " there "); $trimmed = trim(@strings); # $trimmed = "hello there" local $" = ', '; $trimmed = trim(@strings); # Now $trimmed = "hello, there" $trimmed = rtrim; # $trimmed = $_ minus trailing whitespace Undefined values If any of the functions are called with undefined values, the behaviour is in general to pass them through unchanged. When stringifying a list (calling in scalar context with multiple arguments) undefined elements are excluded, but if all elements are undefined then the return value is also undefined. $foo = trim(undef); # $foo is undefined $foo = trim(undef, undef); # $foo is undefined @foo = trim(undef, undef); # @foo contains 2 undefined values trim(@foo) # @foo still contains 2 undefined values $foo = trim('', undef); # $foo is '' FUNCTIONS
trim Removes leading and trailing whitespace from all arguments, or $_ if none are provided. rtrim Like trim() but removes only trailing (right) whitespace. ltrim Like trim() but removes only leading (left) whitespace. UNICODE
Because this module is implemented using perl regular expressions, it is capable of recognising and removing unicode whitespace characters (such as non-breaking spaces) from scalars with the utf8 flag on. See Encode for details about the utf8 flag. Note that this only applies in the case of perl versions after 5.8.0 or so. SEE ALSO
Brent B. Powers' String::Strip performs a similar function in XS. AUTHOR
Matt Lawrence <mattlaw@cpan.org> ACKNOWLEDGEMENTS
Terrence Brannon <metaperl@gmail.com> for bringing my attention to String::Strip and suggesting documentation changes. perl v5.10.1 2010-06-07 Text::Trim(3pm)
