title: perl :"//" operator?
body: <p>I have a question about using "//" operator, my testing code is as following:</p>
  
  <pre><code>perl -e '@arr1=();@arr2=(1,2,3);@arr3=defined(@arr1)?@arr1:@arr2;print "[@arr3]\n"' 
  
  [1 2 3] 
  
  perl -e '@arr1=();@arr2=(1,2,3);@arr3=@arr1//@arr2;print "[@arr3]\n"' 
  
  [0] 
  
  perl -e '$v1=();$v2="123";$v3=defined($v1)?$v1:$v2;print "[$v3]\n"' 
  
  [123] 
  
  perl -e '$v1=();$v2="123";$v3=$v1//$v2;print "[$v3]\n"' 
  
  [123]
  </code></pre>
  
  <p>my question is, why do using "//" operator give the same results as using "defined()? : " on the scalar, but not array(or hash)?</p>
  
  <p>Thanks!!! </p>