Perl – How to format a number to 2 decimal places in Perl

perl

What is best way to format a number to 2 decimal places in Perl?

For example:

10      -> 10.00
10.1    -> 10.10
10.11   -> 10.11
10.111  -> 10.11
10.1111 -> 10.11

Best Answer

It depends on how you want to truncate it.

sprintf with the %.2f format will do the normal "round to half even".

sprintf("%.2f", 1.555);  # 1.56
sprintf("%.2f", 1.554);  # 1.55

%f is a floating point number (basically a decimal) and .2 says to only print two decimal places.

If you want to truncate, not round, then use int. Since that will only truncate to an integer, you have to multiply it and divide it again by the number of decimal places you want to the power of ten.

my $places = 2;
my $factor = 10**$places;
int(1.555 * $factor) / $factor;  # 1.55

For any other rounding scheme use Math::Round.

Related Solutions

Perl – In Perl, how can I limit the number of places after the decimal point but have no trailing zeroes

Use the following directly:

my $s = sprintf('%.3f', $f);
$s =~ s/\.?0*$//;

print $s

...or define a subroutine to do it more generically:

sub fstr {
  my ($value,$precision) = @_;
  $precision ||= 3;
  my $s = sprintf("%.${precision}f", $value);
  $s =~ s/\.?0*$//;
  $s
}

print fstr(0) . "\n";
print fstr(1) . "\n";
print fstr(1.1) . "\n";
print fstr(1.12) . "\n";
print fstr(1.123) . "\n";
print fstr(1.12345) . "\n";
print fstr(1.12345, 2) . "\n";
print fstr(1.12345, 10) . "\n";

Prints:

Perl – How to fix a locale setting warning from Perl

Here is how to solve it on Mac OS X v10.7 (Lion) or Cygwin (Windows 10):

Add the following lines to your bashrc or bash_profile file on the host machine:

# Setting for the new UTF-8 terminal support in Lion
export LC_CTYPE=en_US.UTF-8
export LC_ALL=en_US.UTF-8

If you are using Z shell (zsh), edit file zshrc:

# Setting for the new UTF-8 terminal support in Lion
LC_CTYPE=en_US.UTF-8
LC_ALL=en_US.UTF-8

Best Answer

Related Solutions

Perl – In Perl, how can I limit the number of places after the decimal point but have no trailing zeroes

Perl – How to fix a locale setting warning from Perl

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