Rob Coops wrote:
Thank you all that replied, in the end I copied the rules I learned in
elementary school about how to round a number to two decimals. I'm sure it
is a horrible hack and can be done a lot faster, but with a country not
being able to process their invoices into the accounting system this was the
best way I could come up with that didn't in some cases result in a error.
I am not using any of the suggested modules because the production system is
outside of my control and getting a module installed can take days if not
longer due to processes procedures forms and so on. The country has only a
few days left till the end of the month by which time this should absolutely
be working.
This is the routine as it looks now (I would be happy to hear about errors
or improvements that you might see)
sub round {
my $number = shift;
if ( $number == 0 ) { return 0.00; }
if ( length( $number ) <= 4 ) { return $number; }
my $int = int( $number ); # Get the whole number
my $dec = $number - $int; # Get the decimals only
$dec = sprintf( "%.15f", $dec ) * 1000000000000000;
my @digits = split( //, $dec );
my @reverse_digits = reverse( @digits );
my $number_of_digits = $#reverse_digits - 1;
my $remember = 0;
my $tracker = 0;
for( my $x = 0; $x <= $number_of_digits; $x++ ) {
$reverse_digits[$x] = $reverse_digits[$x] + $remember;
my $result = $reverse_digits[$x] + 5;
if ( $result >= 10 ) {
$remember = 1;
} else {
$remember = 0;
}
$tracker = $x;
}
if ( $reverse_digits[$tracker] >= 10 ) {
$reverse_digits[$tracker] = $reverse_digits[$tracker] - 10;
$reverse_digits[$tracker + 1]++;
if ( $reverse_digits[$tracker + 1] == 10 ) {
$reverse_digits[$tracker + 1] = 0;
$int++;
}
}
my @reordered_digits = reverse(@reverse_digits);
splice( @reordered_digits, 2 );
my $decimal_amount = join( '', @reordered_digits );
return "$int.$decimal_amount";
}
I tried it out. Is this supposed to be correct?
$ perl Perl_rounding_errors.pl
0.524 --> 0.52
0.5241 --> 0.52
0.5242 --> 0.52
0.5243 --> 0.52
0.5244 --> 0.52
0.5245 --> 0.53
0.5246 --> 0.53
0.5247 --> 0.53
0.5248 --> 0.53
0.5249 --> 0.53
John
--
The programmer is fighting against the two most
destructive forces in the universe: entropy and
human stupidity. -- Damian Conway
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