renz has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks, I need to store two portions of a number in two different scalars. For sake of argument we will call the number 2.33 and we will store it in $x. We'll call the two scalars $y and $z. I can easily obtain the first number I need with $y = int($x) but what is the most effective way of storing the decimal portion in $z ? Thanks, /bwb.

Replies are listed 'Best First'.
Re: splitting a decimal number..
by mpeters (Chaplain) on Jan 05, 2005 at 22:47 UTC
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[d/l]
      Hah. Ok. It's been a long day and we'll just pretend I didn't need to be reminded how to subtract.

      /bwb.
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Re: splitting a decimal number..
by punkish (Priest) on Jan 05, 2005 at 22:48 UTC 
    my $x = 2.33;
my $y = int($x);
my $z = $x - $y;

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Re: splitting a decimal number..
by dave_the_m (Monsignor) on Jan 05, 2005 at 22:49 UTC
    er... 
    $y = int $x;
$z = $x  - $y;

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    Of course you may run into problems with negative numbers.

    Dave.

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[d/l]
      Thanks all.
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Re: splitting a decimal number..
by Juerd (Abbot) on Jan 05, 2005 at 22:55 UTC

    This solution is far from perfect, but it *works* (as long as the number stringifies normally) 

    my ($y, $z) = split /\./, $x;

    [download]
    Sometimes you can get away with doing stringy things on numbers. It can be a time saver if you're in a hurry and out of inspiration.

    Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }

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[d/l]
      That's close to how I was trying to do it, but occasionally was yielding some strange results depending on the data I fed to it. Anyway, I've got it worked out now.

      /bwb.
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Re: splitting a decimal number..
by aquarium (Curate) on Jan 06, 2005 at 01:23 UTC
    Depends if you want $z to be 0.23 or just 23, and also depends if you want proper numbers that can be mathematically combined to re-produce original, e.g. $x = -2.23, $y = -2.0, $z = -0.23. If this is the case, or if it's even more complicated, by having to carry proper precision e.g. -2.00, then regexes would work best. if you only care about positive results like $y = 2 and $z = 0.23, then int and subtraction is enough.
    if you're more adventurous: 
    $precision = 100;  # 2 decimal point assumed precision
$x = -2.33;
$y = int($x);
$z = ((abs($x) * $precision) % (abs($y)*$precision)) / $precision;

    [download]
    the hardest line to type correctly is: stty erase ^H
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[d/l]
Re: splitting a decimal number..
by sgifford (Prior) on Jan 06, 2005 at 01:42 UTC
    You can use POSIX::modf: 
    $ perl -MPOSIX -le '
my($f,$i)=POSIX::modf(3.14);
print "f=$f; i=$i";'
f=0.14; i=3

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    That might be more reliable than simple subtraction with negative numbers.

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Re: splitting a decimal number..
by gube (Parson) on Jan 06, 2005 at 03:37 UTC
    Hi, Just try this using split function 
    $x = "2.33";
($y,$z) = split(/\./, $x);
print "$y";
print "\n$z";

o/p:
2
33

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    Regards, Gubendran.L
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[d/l]
Re: splitting a decimal number..
by jbrugger (Parson) on Jan 06, 2005 at 06:16 UTC
    Hi,
    It all depend on what you exactky want. e.g: 
    #!/usr/bin/perl  -t -w

use strict;

sub dosplitMe () {
        my ($x,$justSplitMe) = @_;

        if ($justSplitMe) {
                my ($y, $z) = split(/\./, $x);
                return ($y, $z);
        } else {
                # there might be stuff before first integer...
                my ($y,$z);
                if ($x =~ m/(\D+)?(\d+)\.(\d+)/) {
                        ($y, $z) = ($1.$2 , $1.$3);
                }
                return ($y, $z);
        }
}

my $num1 = 123.456;
my $num2 = -123.456;
my $num3 = "abc123.123";

my @a;
@a = &dosplitMe($num1,1);   print ("1: $a[0] - $a[1] \n");
@a = &dosplitMe($num2,1);   print ("2: $a[0] - $a[1] \n");
@a = &dosplitMe($num2,0);   print ("3: $a[0] - $a[1] \n");
@a = &dosplitMe($num3,1);   print ("4: $a[0] - $a[1] \n");
@a = &dosplitMe($num3,0);   print ("5: $a[0] - $a[1] \n");

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    *** update: *** Or even better: 
    #!/usr/bin/perl  -t -w

use strict;

sub dosplitMe () {
        my ($x,$separator,$justSplitMe) = @_;
        if ($justSplitMe) {
                if ($x =~ m /(.*)?$separator(.*)/) {
                        return ($1,$2);
                }
        } else {
                # there might be stuff before first integer...
                if ($x =~ m/(\D+)?(\d+)$separator(\d+)/) {
                        return ($1.$2 , $1.$3);
                }
        }
}

my $num1 = 123.456;
my $num2 = -123.456;
my $num3 = "abc123,123";

my @a;
@a = &dosplitMe($num1,'\.',1);   print ("1: $a[0] - $a[1] \n");
@a = &dosplitMe($num2,'\.',1);   print ("2: $a[0] - $a[1] \n");
@a = &dosplitMe($num2,'\.',0);   print ("3: $a[0] - $a[1] \n");
@a = &dosplitMe($num3,',', 1);   print ("4: $a[0] - $a[1] \n");
@a = &dosplitMe($num3,',', 0);   print ("5: $a[0] - $a[1] \n");

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