Trimming Blanks from the Ends of a String
Problem
You have read a string that may have leading or trailing whitespace, and you want to remove it.
Solution
Use a pair of pattern substitutions to get rid of them:
$string =~ s/^\s+//; $string =~ s/\s+$//;
You can also write a function that returns the new value:
$string = trim($string);
@many = trim(@many);
sub trim {
my @out = @_;
for (@out) {
s/^\s+//;
s/\s+$//;
}
return wantarray ? @out : $out[0];
}Discussion
This problem has various solutions, but this is the most efficient for the common case.
If you want to remove the last character from the string, use the
chop function. Version 5 added
chomp, which removes the last character if and
only if it is contained in the $/ variable,
"\n" by default. These are often used to remove
the trailing newline from input:
# print what's typed, but surrounded by >< symbols
while(<STDIN>) {
chomp;
print ">$_<\n";
}See Also
The s/// operator in perlre(1) and perlop(1) and the
“Pattern Matching” section of Chapter 2 of
Programming Perl; the
chomp and chop functions in
perlfunc(1) and Chapter 3 of
Programming Perl; we trim leading and
trailing whitespace in the getnum function in
Section 2.1.