On Fri, Oct 25, 2013 at 05:14:23PM -0700, Jim Gibson wrote: > > On Oct 25, 2013, at 4:46 PM, Shaji Kalidasan wrote: > > > Dear Perlers, > > > > I am trying to print the matching lines using __DATA__ filehandle and for > > the very first time it prints the desired lines, but as soon as I rewind it > > using seek, it is printing lines from the very beginning which is not the > > desired result (as it prints from the start). I want to rewind only the > > __DATA__ part. > > As you have discovered, the special file handle DATA is opened to the source > file for your program. When the compiler encounters either of the following > lines in your source file: > > __END__ > __DATA__ > > > it stops reading the source file and leaves the file handle open at that > point. The first time you read the <DATA> file handle, you get the line after > the '__DATA__' line. But when you rewind the file handle, it is positioned at > the beginning of the file, and you get to read your program. > > You have two choices (at least): > > 1. Save the position of the file handle when you enter the program: > > my $data_pos = tell(<DATA>); > > Then reposition the file to this point instead of at the beginning of the > file: > > seek( DATA, $data_pos, 0 ); > > > 2. After rewinding the file to the beginning with seek(DATA,0,0), read the > file until you encounter the '__DATA__' line. Then start reading the data > lines.
The first choice is the correct one. Ideally, you should use the SEEK_SET constant from Fcntl. perldoc Fcntl for details. And for your third approach, you need C< $. = 0; > -- Paul Johnson - p...@pjcj.net http://www.pjcj.net -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
