My first thought was, 'Silly guy, why is he writing C code? Doesn't he know the Perl(tm) way?'.

Then I thought, sprintf() is expensive .... how fast is it to run the integer math?

use strict;
use warnings;
use diagnostics;
 
use Benchmark qw( :all );;
 
my ( $number, $num );
 
$number = 1100.64686081907;
 
cmpthese( -1, {
                sprintf => sub { $num = sprintf "%.2f", $number; },
                round   => sub { $num = int( $number * 100 + .5 ) / 10
+0; },
              }
        );

# produced the results ...

            Rate sprintf   round
sprintf 123242/s      --    -86%
round   851644/s    591%      --

[download]

So integer math rounding is 6 times as fast as using sprintf.

Of course, if you're doing less than 50,000, you may not notice the time difference, especially if you blink.

--
TTTATCGGTCGTTATATAGATGTTTGCA

In reply to Blushing at the facts by TomDLux
in thread Simple Rounding by einerwitzen

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