The <DATA> syntax in perl

Question

Where can I find more about the following syntax in perl?

The connection between <DATA> and __DATA__ is unclear.

while (my $date_string = <DATA>) {   chomp($date_string);   next if not length $date_string;   print "$date_string ist Unixtime ",         $lang_date->str2time($date_string),         " und ",     $lang_date->time2str( '%d.%m.%Y %T (%Z)',$lang_date->str2time($date_string) ),         "\n"; }  __DATA__ 1.3.1999 1 Marz 1999 1. Marz 1999 1/3/1999 

Answer 1

Quoting the doc:

The __DATA__ token tells the perl compiler that the perl code for compilation is finished.

Everything after the __DATA__ token is available for reading via the filehandle FOOBAR::DATA, where FOOBAR is the name of the current package when the __DATA__ token is reached.

This works just the same as __END__ does in package 'main', but for other modules data after __END__ is not automatically retrievable, whereas data after __DATA__ is.

Can add to this only that using __DATA__ section is quite handy to illustrate some file reading-related concepts in Perl. it's basically a file attached to a code, and contents of this file are easily accessible through <DATA>. That's why it's quite popular here on SO. )