Resurrect the TODO items about Unicode filenames and Unicode %ENV

[p5sagit/p5-mst-13.2.git] / pod / perlfaq4.pod

diff --git a/pod/perlfaq4.pod b/pod/perlfaq4.pod
index 7d3a5bc..6a882c5 100644 (file)
--- a/pod/perlfaq4.pod
+++ b/pod/perlfaq4.pod
@@ -1,6 +1,6 @@
 =head1 NAME
 
-perlfaq4 - Data Manipulation ($Revision: 1.49 $, $Date: 2003/09/20 06:37:43 $)
+perlfaq4 - Data Manipulation ($Revision: 1.54 $, $Date: 2003/11/30 00:50:08 $)
 
 =head1 DESCRIPTION
 
@@ -362,9 +362,20 @@ pseudorandom generator than comes with your operating system, look at
 
 =head2 How do I get a random number between X and Y?
 
-Use the following simple function.  It selects a random integer between
-(and possibly including!) the two given integers, e.g.,
-C<random_int_in(50,120)>
+C<rand($x)> returns a number such that
+C<< 0 <= rand($x) < $x >>. Thus what you want to have perl
+figure out is a random number in the range from 0 to the
+difference between your I<X> and I<Y>.
+
+That is, to get a number between 10 and 15, inclusive, you
+want a random number between 0 and 5 that you can then add
+to 10.
+
+    my $number = 10 + int rand( 15-10+1 );
+
+Hence you derive the following simple function to abstract
+that. It selects a random integer between the two given
+integers (inclusive), For example: C<random_int_in(50,120)>.
 
    sub random_int_in ($$) {
      my($min, $max) = @_;
@@ -415,14 +426,6 @@ Use the following simple functions:
        return 1+int((((localtime(shift || time))[5] + 1899))/1000);
     }
 
-You can also use the POSIX strftime() function which may be a bit
-slower but is easier to read and maintain.
-
-       use POSIX qw/strftime/;
-
-       my $week_of_the_year = strftime "%W", localtime;
-       my $day_of_the_year  = strftime "%j", localtime;
-
 On some systems, the POSIX module's strftime() function has
 been extended in a non-standard way to use a C<%C> format,
 which they sometimes claim is the "century".  It isn't,
@@ -1489,16 +1492,11 @@ the hash is to be modified.
 
 Use the rand() function (see L<perlfunc/rand>):
 
-    # at the top of the program:
-    srand;                     # not needed for 5.004 and later
-
-    # then later on
     $index   = rand @array;
     $element = $array[$index];
 
-Make sure you I<only call srand once per program, if then>.
-If you are calling it more than once (such as before each
-call to rand), you're almost certainly doing something wrong.
+Or, simply:
+    my $element = $array[ rand @array ];
 
 =head2 How do I permute N elements of a list?
 
@@ -1586,7 +1584,7 @@ If you need to sort on several fields, the following paradigm is useful.
 This can be conveniently combined with precalculation of keys as given
 above.
 
-See the F<sort> artitcle article in the "Far More Than You Ever Wanted
+See the F<sort> article in the "Far More Than You Ever Wanted
 To Know" collection in http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz for
 more about this approach.