Trim a string in perl

problem:
I am a perl noob and i need trim a string.

solution:
1) if i can modify the actual string:
sub trim {$_[0] =~s/^\s+|\s+$//g}

2)if i don't want it to modify:
sub trim {my $s = $_[0]; $s=~s/^\s+|\s+$//g;return $s;}