Finding number of lines in STDIN

bonoboy has asked for the wisdom of the Perl Monks concerning the following question:

Morning. I've got a subroutine which I'm using for parsing user input from STDIN. I'd like to add functionality to restrict the number of lines a user can input, while still using 'while'. The way I'd thought I might be able to do it is like this:

if(defined($number_of_lines)) {  
            if($#_ eq $number_of_lines) {
                last;
            }
        }
[download]

As I figured STDIN might be read into @_. It's giving me syntax errors though. Was that a wrong assumption about @_? And if so, how would you do it? And if it's not, is my syntax just crappy?

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Comment on Finding number of lines in STDIN Download Code

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Re: Finding number of lines in STDIN by castaway (Parson) on Dec 18, 2003 at 11:21 UTC
There's a perl variable which counts lines on a filehandle, and works on STDIN, it's called $.. So just do something like: `last if($. == $number_of_lines);` [download] (To compare numbers, use '==' not 'eq') Note: $. is the line count for the last filehandle accessed, so dont use it if you're accessing other files inbetween. C.	[reply] [d/l]
Re: Re: Finding number of lines in STDIN by ysth (Canon) on Dec 18, 2003 at 16:32 UTC
Clarification: `$.` is the line count for the last filehandle accessed by and of: readline (aka <>), tell(FILEHANDLE), seek, or sysseek. You can access the line count for any filehandle with `some_filehandle->input_line_number` (but you have to `use FileHandle` or `use IO::Handle` first). Note that `STDIN->input_line_number` is tracked separately from `ARGV->input_line_number` even when `<ARGV>` or empty `<>` is reading from stdin.	[reply] [d/l] [select]
Re: Finding number of lines in STDIN by bart (Canon) on Dec 18, 2003 at 11:17 UTC
Try `while(<>) { last if $number_of_lines && $. > $number_of_lines; ... }` [download] $. is an automatic counter for the line numbers. (See perlvar)	[reply] [d/l]