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Diffstat (limited to 'pod/perlfaq4.pod')
| -rw-r--r-- | pod/perlfaq4.pod | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/pod/perlfaq4.pod b/pod/perlfaq4.pod index 22ea1ae581..0966139224 100644 --- a/pod/perlfaq4.pod +++ b/pod/perlfaq4.pod @@ -1,6 +1,6 @@ =head1 NAME -perlfaq4 - Data Manipulation ($Revision: 1.73 $, $Date: 2005/12/31 00:54:37 $) +perlfaq4 - Data Manipulation ($Revision: 3606 $) =head1 DESCRIPTION @@ -362,6 +362,9 @@ pseudorandom generator than comes with your operating system, look at =head2 How do I get a random number between X and Y? +To get a random number between two values, you can use the +C<rand()> builtin to get a random number between 0 and + C<rand($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 @@ -371,19 +374,19 @@ 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 ); + 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 ($$) { - my($min, $max) = @_; - # Assumes that the two arguments are integers themselves! - return $min if $min == $max; - ($min, $max) = ($max, $min) if $min > $max; - return $min + int rand(1 + $max - $min); - } +integers (inclusive), For example: C<random_int_between(50,120)>. + + sub random_int_between ($$) { + my($min, $max) = @_; + # Assumes that the two arguments are integers themselves! + return $min if $min == $max; + ($min, $max) = ($max, $min) if $min > $max; + return $min + int rand(1 + $max - $min); + } =head1 Data: Dates @@ -2153,6 +2156,14 @@ The kgbpack.c code in the PGPLOT module on CPAN does just this. If you're doing a lot of float or double processing, consider using the PDL module from CPAN instead--it makes number-crunching easy. +=head1 REVISION + +Revision: $Revision: 3606 $ + +Date: $Date: 2006-03-06 12:05:47 +0100 (lun, 06 mar 2006) $ + +See L<perlfaq> for source control details and availability. + =head1 AUTHOR AND COPYRIGHT Copyright (c) 1997-2006 Tom Christiansen, Nathan Torkington, and |