Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

Re: grep flip flop (range operator)

by Neighbour (Friar)
on Sep 13, 2012 at 06:42 UTC ( #993380=note: print w/ replies, xml ) Need Help??


in reply to grep flip flop (range operator)

What are you expecting to get with 1 .. /Q/?
The following code prints nothing as well:

use Data::Dump; Data::Dump::dd(1 .. /Q/);
If your match-list is empty, nothing matches, and nothing is printed.
However, this does not explain why the last command *does* print something :)

Edit: Upon further reading, it looks like the range operator isn't parsed in scalar context, as the following does print something: perl -le " print for grep scalar 1 .. /Q/, @ARGV " a b c Q r s

Output: a b c Q r s


Comment on Re: grep flip flop (range operator)
Select or Download Code
Re^2: grep flip flop (range operator)
by Anonymous Monk on Sep 13, 2012 at 07:04 UTC

    Edit: Upon further reading, it looks like the range operator isn't parsed in scalar context, as the following does print something: perl -le " print for grep scalar 1 .. /Q/, @ARGV " a b c Q r s

    I use    perl -MO=Deparse,-p   what you have is  (scalar(1) .. /Q/)

    you need  scalar( 1 .. /Q/ ) to get nothing :)

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://993380]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others musing on the Monastery: (14)
As of 2015-07-07 14:28 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 (89 votes), past polls