Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things
 
PerlMonks  

Re: shift and logical or

by Kenosis (Priest)
on Nov 16, 2012 at 23:19 UTC ( #1004266=note: print w/ replies, xml ) Need Help??


in reply to shift and logical or

Consider the following:

use strict; use warnings; printSomething('Hello, world.'); printSomething(); sub printSomething { my $string = shift || 'Nothing was sent.'; print $string, "\n"; }

First output:

Hello, world.

Second output:

Nothing was sent.

In subroutines, shift takes the first element off @_. In the case above, $string is initialized with whatever is sent to the subroutine. However, if nothing is sent, $string is initialized with 'Nothing was sent.' This is because of the logical or operation in Perl. If the first disjunct (shift) evaluates to true, then Perl stops there, since the overall express is true. However if the first disjunct evaluates to false (nothing to shift), Perl moves to the second disjunct. Thus, printSomething() prints Nothing was sent. Here's another way to 'say' this: the variable $string equals either what was sent to the subroutine or the string 'Nothing was sent.'


Comment on Re: shift and logical or
Select or Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1004266]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others browsing the Monastery: (7)
As of 2014-12-20 21:43 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    Is guessing a good strategy for surviving in the IT business?





    Results (99 votes), past polls