Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

Re^3: command line perl reading from STDIN

by perlhappy (Novice)
on Jan 22, 2013 at 18:12 UTC ( #1014749=note: print w/ replies, xml ) Need Help??


in reply to Re^2: command line perl reading from STDIN
in thread command line perl reading from STDIN

Actually, I think I've just worked it out my head. Took a bit of thinking but this is what i think it is doing
first line gets sent, but because <> is unassigned (before $s), it skips; then reads the second line and assigns $s to the line and does whatever; then reads third line but because <> is unassigned, it skips; reads fourth line and the same happens; restarts with 5 line but again because <> is unassigned before the $s it skips; reads 6th line and assigns it to $s and does whatever again
this continues until end of file

If this is incorrect, let me know. Otherwise I hope this helps anyone else who might look at it. Thanks for your help choroba


Comment on Re^3: command line perl reading from STDIN
Replies are listed 'Best First'.
Re^4: command line perl reading from STDIN
by Anonymous Monk on Jan 23, 2013 at 23:32 UTC
     perl -ne ' $s=<>; <>; <>; do_something_with_$s'

    is equivalent to

     perl  -e ' while (<>) { $s=<>; <>; <>; do_something_with_$s} '

    so 4 lines will be read each pass, but only the second line will be used for anything

    Personally, I'd go with something like

     perl -ne 'chomp; print length($_)."\n" if (/^@/);'

    instead.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1014749]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (12)
As of 2015-07-31 10:00 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (276 votes), past polls