Range function

[Xah Lee]

Here's the Perl code.

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#! perl

# http://xahlee.org/tree/tree.html
# Xah Lee, 2005-05

#_____ Range _____ _____ _____ _____

=pod

B<Range>

Range($iMax) generates the list [1, 2, ... , $iMax].

Range($iMin, $iMax) generates the list [$iMin, ... , $iMax].

Range($iMin, $iMax, $iStep) uses increment $iStep, with the last
element in the result being less or equal to $iMax. $iStep cannot be 0.
If $iStep is negative, then the role of $iMin and $iMax are reversed.

If Range fails, 0 is returned.

Example:

 Range(5); # returns [1,2,3,4,5]

 Range(5,10); # returns [5,6,7,8,9,10]

 Range( 5, 7, 0.3); # returns [5, 5.3, 5.6, 5.9, 6.2, 6.5, 6.8]

 Range( 5, -4, -2); # returns [5,3,1,-1,-3]

=cut

sub Range ($;$$) {
if (scalar @_ == 1) {return _rangeFullArgsWithErrorCheck(1,$_[0],1);};
if (scalar @_ == 2) {return
_rangeFullArgsWithErrorCheck($_[0],$_[1],1);};
if (scalar @_ == 3) {return
_rangeFullArgsWithErrorCheck($_[0],$_[1],$_[2]);};
};

sub _rangeFullArgsWithErrorCheck ($$$) {
my ($a1, $b1, $dx) = @_;

if ($dx == 0) {print "Range: increment cannot be zero."; return 0}
elsif ($a1 == $b1) {return [$a1];}
elsif ( ((($b1 - $a1) > 0) && ($dx < 0)) || ((($b1 - $a1) < 0) && ($dx
> 0)) ) {print "Range: bad arguments. You have [$a1,$b1,$dx]"; return
0;}
elsif ((($a1 < $b1) && ($b1 < ($a1 + $dx))) || (($a1 > $b1) && ($b1 >
($a1 + $dx)))) {return [$a1];}
else { return _rangeWithGoodArgs ($a1,$b1,$dx);};
};

sub _rangeWithGoodArgs ($$$) {
my ($a1, $b1, $dx) = @_;
my @result;

if ($a1 < $b1) {for (my $i = $a1; $i <= $b1; $i += $dx) { push
(@result, $i);}; }
else {for (my $i = $a1; $i >= $b1; $i += $dx) { push (@result, $i);};
};
return \@result;
};

#end Range

##########
# test

use Data::Dumper;
print Dumper(Range(5,7,0.3));