Using the Perl chomp() function
Introduction
The
chomp() function will remove (usually) any
newline character from the end of a string. The reason we say usually is that it
actually removes any character that matches the current value of $/ (the input
record separator), and $/ defaults to a newline.
For more information on the $/ variable, try
perldoc
perlvar and see the entry for $/. Example 1. Chomping a string
Most often you will use
chomp() when reading data
from a file or from a user. When reading user input from the standard input
stream (STDIN) for instance, you get a newline character with each line of data.
chomp() is really useful in this case because you do not need to
write a regular expression and you do not need to worry about it removing needed
characters.
When running the example below, using the enter key on a line
by itself will exit the program.
#!/usr/bin/perl use strict; use warnings; while (my $text =) { chomp($text); print "You entered '$text'\n"; last if ($text eq ''); }
Example usage and output of this program is:
a word You entered 'a word' some text You entered 'some text' You entered ''
Example 2. Chomping an array
If you chomp an array, it will remove a newline from the end
of every element in the array:
#!/usr/bin/perl
use strict;
use warnings;
my @array = ("bob\n", "jill", "fred\n");
print "Before chomp:\n";
print "@array\n";
chomp(@array);
print "After chomp:\n";
print "@array\n";
This program produces the following output:
Before chomp: bob jill fred After chomp: bob jill fred
As you can see, the newlines have been removed from "bob" and
"fred", but no characters have been removed from "jill".
Example 3. Chomping a hash
If you pass a hash into
chomp(), it will remove
newlines from every value (not key) of the hash: #!/usr/bin/perl
use strict;
use warnings;
my %hash = (
'first' => "one\n",
'second' => "two\n",
'third' => "three\n",
);
chomp(%hash);
foreach my $k (keys %hash) {
print "$k: $hash{$k} ";
}
print "\n";
exit 0;
This program outputs:
first: one second: two third: three
