On 15 May 2005 02:50:38 -0700, Xah Lee <[EMAIL PROTECTED]> wrote: > Here's the Perl code.
Where did you learn to program? Its highly unlikely that a Perl programer would ever write a range function as there is a built in Perl function that does the same thing. If your intent is purely accedemic then the first thing you should do is learn Perl to a much higher grade. > #! perl > > # http://xahlee.org/tree/tree.html > # Xah Lee, 2005-05 > > #_____ Range _____ _____ _____ _____ > >=pod > > B<Range> Its considered poor style to have function names with capital letters. The normal convention is to use all lower case. > 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 $iMax are reversed. > > If Range fails, 0 is returned. > > Example: > > Range(5); # returns [1,2,3,4,5] > > Range(5,10); # returns [5,6,7,8,9,10] > > Range( 5, 7, 0.3); # returns [5, 5.3, 5.6, 5.9, 6.2, 6.5, 6.8] > > Range( 5, -4, -2); # returns [5,3,1,-1,-3] > >=cut sub range { return [1..$_[0]] if (@_==1); return [$_[0]..$_[1]] if (@_==2); my $lowest = shift; my $greatest = shift; my $increment = shift; my $steps = ($greatest - $lowest)/$increment; my @return = map { $_ * $increment + $lowest } (0..$steps); return [EMAIL PROTECTED]; } This does as you wish but it far shorter and I would argue easyer for the typical perl programer to read. > sub Range ($;$$) { > if (scalar @_ == 1) {return _rangeFullArgsWithErrorCheck(1,$_[0],1);}; > if (scalar @_ == 2) {return > _rangeFullArgsWithErrorCheck($_[0],$_[1],1);}; > if (scalar @_ == 3) {return > _rangeFullArgsWithErrorCheck($_[0],$_[1],$_[2]);}; >}; I would suggest that If you have the case where your doing a one line if stament then you should make use of the line modifing verent of if. Also since if produces a scalar context its not needed. sub Range ($;$$) { return _rangeFullArgsWithErrorCheck(1,$_[0],1) if (@_ == 1); return _rangeFullArgsWithErrorCheck($_[0],$_[1],1) if (@_ == 2); return _rangeFullArgsWithErrorCheck($_[0],$_[1],$_[2]) if (@_ == 3); } See how much neater and more readable the code is after doing that. > sub _rangeFullArgsWithErrorCheck ($$$) { > my ($a1, $b1, $dx) = @_; > > if ($dx == 0) {print "Range: increment cannot be zero."; return 0} > elsif ($a1 == $b1) {return [$a1];} > elsif ( ((($b1 - $a1) > 0) && ($dx < 0)) || ((($b1 - $a1) < 0) && ($dx >> 0)) ) {print "Range: bad arguments. You have [$a1,$b1,$dx]"; return > 0;} > elsif ((($a1 < $b1) && ($b1 < ($a1 + $dx))) || (($a1 > $b1) && ($b1 > > ($a1 + $dx)))) {return [$a1];} > else { return _rangeWithGoodArgs ($a1,$b1,$dx);}; >}; This would be a great place to make use of die. Throwing an exection for an error. sub _rangeFullArgsWithErrorCheck ($$$) { my ($a1, $b1, $dx) = @_; die "Range: increment cannot be zero." unless $dx; return [$a1] if ($a1 == $b1); if ( ((($b1 - $a1) > 0) && ($dx < 0)) || ((($b1 - $a1) < 0) && ($dx0))) { die "Range: bad arguments. You have [$a1,$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 [EMAIL PROTECTED]; >}; Personally I don't like the c style while loop. I didn't like it in C and I don't like it in perl. -- Please excuse my spelling as I suffer from agraphia. See http://dformosa.zeta.org.au/~dformosa/Spelling.html to find out more. Free the Memes. -- http://mail.python.org/mailman/listinfo/python-list
