How can I convert between scientific and decimal notation in Perl?

I know this is a total newbi开发者_StackOverflow中文版e question, but the answer may not be obvious to many new programmers. It wasn't initially obvious to me so I scoured the Internet looking for Perl modules to do this simple task.

sprintf does the trick

use strict;
use warnings;

my $decimal_notation = 10 / 3;
my $scientific_notation = sprintf("%e", $decimal_notation);

print "Decimal ($decimal_notation) to scientific ($scientific_notation)\n\n";

$scientific_notation = "1.23456789e+001";
$decimal_notation = sprintf("%.10g", $scientific_notation);

print "Scientific ($scientific_notation) to decimal ($decimal_notation)\n\n";

generates this output:

Decimal (3.33333333333333) to scientific (3.333333e+000)

Scientific (1.23456789e+001) to decimal (12.3456789)

On a related theme, if you want to convert between decimal notation and engineering notation (which is a version of scientific notation), the Number::FormatEng module from CPAN is handy:

use Number::FormatEng qw(:all);
print format_eng(1234);     # prints 1.234e3
print format_pref(-0.035);  # prints -35m
unformat_pref('1.23T');     # returns 1.23e+12