perlfaq4: How can I tell whether a certain element is contained in a list or array?

[_brian_d_foy]

replaces "associative array" with "hash"

clears aggregates with "= ()" rather than undef-ing them.


Index: perlfaq4.pod
===================================================================
RCS file: /cvs/public/perlfaq/perlfaq4.pod,v
retrieving revision 1.15
diff -u -d -r1.15 perlfaq4.pod
--- perlfaq4.pod        21 Feb 2002 14:48:01 -0000      1.15
+++ perlfaq4.pod        21 Feb 2002 14:53:37 -0000
@@ -1,6 +1,6 @@
 =head1 NAME
 
-perlfaq4 - Data Manipulation ($Revision: 1.15 $, $Date: 2002/02/21 14:48:01 $)
+perlfaq4 - Data Manipulation ($Revision: 1.14 $, $Date: 2002/02/08 22:30:23 $)
 
 =head1 DESCRIPTION
 
@@ -1130,11 +1130,11 @@
 
 That being said, there are several ways to approach this.  If you
 are going to make this query many times over arbitrary string values,
-the fastest way is probably to invert the original array and keep an
-associative array lying about whose keys are the first array's values.
+the fastest way is probably to invert the original array and maintain a
+hash whose keys are the first array's values.
 
     @blues = qw/azure cerulean teal turquoise lapis-lazuli/;
-    undef %is_blue;
+    %is_blue = ();
     for (@blues) { $is_blue{$_} = 1 }
 
 Now you can check whether $is_blue{$some_color}.  It might have been a
@@ -1144,7 +1144,7 @@
 array.  This kind of an array will take up less space:
 
     @primes = (2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31);
-    undef @is_tiny_prime;
+    @is_tiny_prime = ();
     for (@primes) { $is_tiny_prime[$_] = 1 }
     # or simply  @istiny_prime[@primes] = (1) x @primes;