Re^4: Negative zero? There's gotta be a sprintf that undoes that, right?

Well, something is to be said for approaching a problem from different points of view and uncovering new truths. So I'll give it a try.

The solution wasn't as smooth as I'd hope, apparently -0.0 == 0.

my $sign = "";
my $number = -0.000001;

my $example = sprintf("%.5f", $number);
#$example = $number; #uncomment this, to remove the initial rounding

print "A. Started with : $example \n";
if ($example < 0) {
    $example = -$example;    
    $sign = "-";

    print "B. Less than zero: changed to  $example \n";
}

print "C. the number is $example \n";
if ($example == 0 )
{
    print "D1. the number ($example) is equal to zero, removing the si
+gn.\n";
    $example *= -1; #(couldn't hurt, it's zero)
    print "D2. the number ($example) is equal to zero, removing the si
+gn.\n";
    $sign = '';
}

print "E. proceeding to sprint $example with sign $sign .\n";
$tret = sprintf("rounded float: %s%7.5f : unrounded %7.5f", $sign, $ex
+ample, $number);
print "$tret \n";
[download]

Output:

A. Started with : -0.00000 
C. the number is -0.00000 
D1. the number (-0.00000) is equal to zero, removing the sign.
D2. the number (0) is equal to zero, removing the sign.
E. proceeding to sprint 0 with sign  .
rounded float: 0.00000 : unrounded -0.00000

Comment on Re^4: Negative zero? There's gotta be a sprintf that undoes that, right? Download Code

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Re^5: Negative zero? There's gotta be a sprintf that undoes that, right? by roboticus (Chancellor) on Dec 11, 2007 at 20:22 UTC
rgiskard: Clearly I was wrong. ;^) But I have another idea--and it's a bit shorter than the last one! `$example = abs($example) if abs($example) < 0.00001;` [download] I hope this one is better than the last one... Unfortunately, I've gotta pick up my son from school, so this one too is untested. ;^( ...roboticus	[reply] [d/l]
Re^5: Negative zero? There's gotta be a sprintf that undoes that, right? by suaveant (Parson) on Dec 12, 2007 at 14:14 UTC
Ironically, "-0.0" == 0 BUT triggers true in an \|\|... using that, however you CAN do... `$num = '-0.0000009'; $num = sprintf("%7.5f",$num); $num = $num == 0 ? '0.00000' : $num; print "$num\n";` [download] I was hoping \|\| would work, cuz then you could do `$num = sprintf("%7.5f",$num) \|\| '0.00000';` [download] but alas, no. The following works... `$num = sprintf("%7.5f",$num)+0 \|\| '0.00000';` [download] but you lose all trailing zeros, which works if you only want to round, but not for formatting, so probably doesn't help. - Ant - Some of my best work - (1 2 3)	[reply] [d/l] [select]