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How do I print/round a number to a given number of decimal places?

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Contributed by vroom on Jan 08, 2000 at 08:23 UTC
Q&A  > data formatting


Answer: How do I print/round a number to a given number of decimal places?
contributed by vroom

Probably the easiest way is to use printf/sprintf:

$unrounded = 0.66666; printf "$unrounded rounded to 3 decimal places is %.3f\n", $unrounded; $rounded = sprintf "%.2f", $a; # rounded to 2 decimal places (0.67)
Answer: How do I print/round a number to a given number of decimal places?
contributed by hossman

As in How do I round a number?Math::Round has a great method for this:

use Math::Round; print nearest(.01, 1.555);

Answer: How do I print/round a number to a given number of decimal places?
contributed by Roy Johnson

This other answer, by wrvhage, has the great property of working correctly for values like 3.005 rounded to two places (where sprintf is not). However, it needs a couple of tweaks to work for negative numbers.

sub stround { my( $n, $places ) = @_; my $sign = ($n < 0) ? '-' : ''; my $abs = abs $n; $sign . substr( $abs + ( '0.' . '0' x $places . '5' ), 0, $places ++ length(int($abs)) + 1 ); }

Answer: How do I print/round a number to a given number of decimal places?
contributed by wrvhage

sub stround { my( $number, $decimals ) = @_; substr( $number + ( '0.' . '0' x $decimals . '5' ), 0, $decimals + + length(int($number)) + 1 ); }
TIMTOWTDI!

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