Arrays and Hashes

Shifting and Unshifting

• The push and pop operators operate on the right side of the array.
• Perl also supports unshift and shift operations, that are exactly analgous to push and pop, but operate on the left side of the array.
• Example:
  

  unshift ( @First, 1); 
  unshift ( @First, 2); 
  unshift ( @First, 3); 
  $Result = shift(@First);
  print "$Result"; 
  $Result = shift(@First);
  print "$Result"; 
  $Result = shift(@First);
  print "$Result\n"; 
  ==> 3 2 1 
  

• push, pop, shift, and unshift can all be used interchangably to implement whatever kind of stack you wish.