Re: What is this called: ($myvar-{otherid}) ? 'stringA' : 'stringB';

[R. Joseph Newton]

Jeff Kowalczyk wrote:

 I'm not yet able to read certain parts of perl code. What is this
 comparison/alternation after the hash lookup on 'otherid' called, and what
 does the code do?

 $myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';

 Thanks.

That is the conditional operator.

Joseph


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What is this called: ($myvar-{otherid}) ? 'stringA' : 'stringB';

[Jeff Kowalczyk]

I'm not yet able to read certain parts of perl code. What is this
comparison/alternation after the hash lookup on 'otherid' called, and what
does the code do?

$myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';

Thanks.


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Re: What is this called: ($myvar-{otherid}) ? 'stringA' : 'stringB';

[Morbus Iff]

I'm not yet able to read certain parts of perl code. What is this
comparison/alternation after the hash lookup on 'otherid' called, and what
does the code do?

  $myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';
It's a ternary or flip-flop statement. In
this case, the above is the equivalent of:
 if myvar-otherid is set, then set myvar-id to
  stringA, otherwise, set it to stringB.
Code-wise, the above is equivalent to:

 if ($myvar-{otherid}) { $myvar-{id} == 'stringA' };
 else   { $myvar-{id} == 'stringB'; }
--
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Culture: http://www.disobey.com/ and http://www.gamegrene.com/
My book, Spidering Hacks: http://amazon.com/exec/obidos/ASIN/0596005776/
icq: 2927491 / aim: akaMorbus / yahoo: morbus_iff / jabber.org: morbus
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Re: What is this called: ($myvar-{otherid}) ? 'stringA' : 'stringB';

[Kevin Old]

On Thu, 2003-11-20 at 15:18, Jeff Kowalczyk wrote:
 I'm not yet able to read certain parts of perl code. What is this
 comparison/alternation after the hash lookup on 'otherid' called, and what
 does the code do?
 
 $myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';
 
 Thanks.

Jeff,

This is the if-then-else operator (for lack of a better term).

The code above could be translated to:

if ($myvar-{otherid}) {
$myvar-{id} = 'stringA';
} else {
$myvar-{id} = 'stringB';
}



From 'perldoc perlop':

Ternary ?: is the conditional operator, just as in C.  It works much
like an if-then-else.  If the argument before the ? is true, the argu-
ment before the : is returned, otherwise the argument after the : is
returned.  For example:

   printf I have %d dog%s.\n, $n,
   ($n == 1) ? '' : s


HTH,
Kevin
-- 
Kevin Old [EMAIL PROTECTED]


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Re: What is this called: ($myvar-{otherid}) ? 'stringA' : 'stringB';

[drieux]

On Thursday, Nov 20, 2003, at 12:18 US/Pacific, Jeff Kowalczyk wrote:

I'm not yet able to read certain parts of perl code. What is this
comparison/alternation after the hash lookup on 'otherid' called, and 
what
does the code do?

$myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';

it is short for

if ($myvar-{otherid})
{
$myvar-{id} = 'stringA';
}else{
$myvar-{id} = 'stringB';
}
so you too might like Data::Dumper and go with
a short script like:
#!/usr/bin/perl -w
use strict;
use Data::Dumper;
# #FILENAME# - is for


my $myvar = { otherid = 'bob', id = 'alice' };

print Dumper $myvar ;

$myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';

print Dumper $myvar ;

delete $myvar-{otherid};

$myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';

print Dumper $myvar ;
which generates

$VAR1 = {
  'otherid' = 'bob',
  'id' = 'alice'
};
$VAR1 = {
  'otherid' = 'bob',
  'id' = 'stringA'
};
$VAR1 = {
  'id' = 'stringB'
};
ciao
drieux
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Re: What is this called: ($myvar-{otherid}) ? 'stringA' : 'stringB';

[John W. Krahn]

Jeff Kowalczyk wrote:
 
 I'm not yet able to read certain parts of perl code. What is this
 comparison/alternation after the hash lookup on 'otherid' called, and what
 does the code do?
 
 $myvar-{id} = ($myvar-{otherid}) ? 'stringA' : 'stringB';

perldoc perlop
[snip]
   Conditional Operator

   Ternary ?: is the conditional operator, just as in C.
   It works much like an if-then-else.  If the argument
   before the ? is true, the argument before the : is
   returned, otherwise the argument after the : is returned.



John
-- 
use Perl;
program
fulfillment

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