convert a string to number and divide 2

[jcarrott]

I know this is basic a stupid, am sorry.

I am retrieving a value from a table and I need to divide it by another value that I have retrieved.

The current code does not work.

# read POVAGRMTLN table
        my $stmt = "SELECT POVAGRMTLN.BASE_COST
           FROM LAWSON.POVAGRMTLN
           WHERE POVAGRMTLN.PROCURE_GROUP  = '" . $vVendGr . "' AND
                 POVAGRMTLN.ITEM           = '" . $vItem . "' AND
                 POVAGRMTLN.HOLD_FLAG      = '" . $vFlag . "'";

        my @rev = $dbh->selectrow_array($stmt);
        $field[23] = printf "%10.4f"($rev[0] / $vConv);

        print OU2 join('|', $vItem, $vConv, $field[23], "\n");

I am trying to define $rev[0] and $vConv to both be of a length of 10 and a decimal precission of 4. With that result going into $field[23]. Do I need to define each separately then do the math?

 

[mikrom]

I tried to divide 2 strings which contain numbers, but it seems to work without problem.
For example, this code

use strict;
use warnings;

my $str01 = '3.14159';
my $str02 = '2.0';
my $res = $str01/$str02;

print "\$str01 = $str01, \$str02 = $str02, \$res=\$str01/\$str02 = $res\n";

gives this output:

c:\Work>perl str2num.pl
$str01 = 3.14159, $str02 = 2.0, $res=$str01/$str02 = 1.570795

 

[prex1]

OK, it does not work, but what is it giving?
The [tt]printf[/tt] is incorrect, there should be a comma after the format string.

Franco

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[rharsh]

I'm going to assume that all the lines leading up to the 'printf' line are working. For the calculation you're trying to do, you want to use sprintf. Something like this will probably work for you:

$field[23] = [red][b]s[/b][/red]printf "%10.4f"[red][b], [/b][/red]($rev[0] / $vConv);

Now that is going to lead to a problem with half-way-point alternation (take a look at perlfaq4 for an explanation.)

In the past, I have used a function similar to the one in the following code to do rounding. I'm sure it could be made to run faster but it's worked for me.

foreach (@arr) {
	my $temp = sprintf '%10.4f', myround($_, 4);
	print $temp, "\n";
}

sub myround {
	my ($float, $precision) = @_;
	my $capture = $precision + 1; #number of decimal places to capture
	if (m/([^.]+)(\.\d{$capture})/) {
		my ($ant, $cons) = ($1, $2);
		$cons = int($cons * 10**($precision)+0.5) * 10**(-$precision);
		$cons = $cons * -1 if $ant < 0;
		return $ant + $cons;
	} else {
		return $float;
	}
}