Re: Rounding problem with sprintf??

This is a known "bug". It happens like that in C as well. Write your own rounding function, or use this one:

# round(789.456,-2) => 800
# round(789.456,-1) => 790
# round(789.456)    => 789
# round(789.456,1)  => 789.5
# round(789.456,2)  => 789.46

sub round {
  my ($n, $p) = @_;
  my $sign = ($n > 0) ? 1 : -1;

  $p ||= 0;
  $n *= 10 ** $p;
  $n = int($n + .5 * $sign);
  return $n / 10**$p;
}
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Comment on Re: Rounding problem with sprintf?? Download Code

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Re^2: Rounding problem with sprintf?? by Anonymous Monk on Sep 04, 2014 at 07:26 UTC
This sub has the same bug as `sprintf`. `round(5.245,2)` returns `5.25` but `round(9.325,2)` returns `9.32`	[reply] [d/l] [select]
Re^3: Rounding problem with sprintf?? by AnomalousMonk (Archbishop) on Sep 04, 2014 at 15:56 UTC
But again, the root 'bug' is in floating point, which cannot exactly represent the numbers you give. See What Every Computer Scientist Should Know About Floating-Point Arithmetic. `c:\@Work\Perl>perl -wMstrict -le "for my $f (5.245, 9.325) { print sprintf '%.20f', $f; } " 5.24500000000000010000 9.32499999999999930000` [download] Update: Slight cosmetic change to code example.	[reply] [d/l]