Perl Code Examples

Rounding

Rounds a number to the specified number of decimal places.

# Sample code
print round(12.456, 2);	# prints 12.46

# Subroutine
sub round {
	my ($number, $places) = @_;
	$places = 10 ** $places;
	return int(($number * $places) + .5 * ($number <=> 0)) / $places;
}

Build a Set Value for MySQL

The purpose of this routine is to build the set value for an SQL INSERT or UPDATE.
This could be used to build WHERE clauses by changing $comma to AND or OR as appropriate.

# Sample code
use DBI;
$dbh = DBI->connect ($dsn, $user, $password);

$set = '';
$set = add_to_set($set, "name", $name);
$set = add_to_set($set, "address", $address);
$sql = "UPDATE employee SET $set WHERE empl_id = $empl_id";

# Subroutines
sub add_to_set {
	my ($set, $field, $value) = @_;
	my $comma = '';
	$comma = ',' if ( $set );
	$value = $dbh->quote($value);
	return "$set$comma$field=$value";
}

Comma Edit a Number

Inserts commas in a number.

# Sample code
print commify(123456789.8765);

# Subroutine
sub commify {
	my $number = shift;
	$number = reverse $number;
	$number =~ s/(\d{3})(?=\d)(?!\d*\.)/$1,/g;
	$number = reverse $number;
	return $number;
}

sub uncommify {
	my $number = shift;
	$number =~ s/,//g;
	return $number;
}

Extract and Validate a Date

Output format is YYYY-MM-DD. If needed, add handling to convert 2 digit years.

# Sample code
print date_edit("September 15, 2009");	# prints 2009-09-15
print date_edit("Fecember 15, 2009");	# prints 0000-00-00
print date_edit("7-1-09");		# prints 0009-07-01
print date_edit("2009/12/1");		# prints 2009-12-01
print date_edit("6 Mar 2009");		# prints 2009-03-06

# Subroutine
sub date_edit {
	my $date = shift;
	my $mo, $da, $yr;

	# Dates may be edited with any non-digit character.
	# Numeric month and day may be 1 or 2 numbers.
	# Alpha month is not case sensitive.
	# Alpha month must contain at least three of the first characters.
	# Year may be 2 or 4 numbers.

	# looking for MM-DD-YYYY (i.e. 1/12/2009)
	if ( $date =~ /(\d{1,2})\D+(\d{1,2})\D+(\d{4}|\d{2})\D*$/ ) {
		$mo = $1;
		$da = $2;
		$yr = $3;

	# looking for YYYY-MM-DD  (i.e. 2009-01-12)
	} elsif ( $date =~ /^\D*(\d{4}|\d{2})\D+(\d{1,2}?)\D+(\d{1,2}?)/ ) {
		$yr = $1;
		$mo = $2;
		$da = $3;

	# looking for DD monthname YYYY (i.e. 12 January 2009)
	} elsif ( $date =~ /(\d{1,2})\D+(.+?)\s+(\d{4}|\d{2})\D*$/ ) {
		$da = $1;
		$yr = $3;
		$mo = getMoNo($2);

	# looking for monthname DD, YYYY (i.e. January 12, 2009)
	} elsif ( $date =~ /(.+?)\D+(\d{1,2})\D+(\d{4}|\d{2})\D*$/ ) {
		$da = $2;
		$yr = $3;
		$mo = getMoNo($1);
	}

	if ( $mo >= 1 && $mo <= 12 ) {
		if ( $da >= 1
			&& $da <= (0,31,28+isLeapYear($yr),31,30,31,30,31,31,30,31,30,31)[$mo]) {
				# Two digit year processing, customize for your application
				# if ( $yr < 100 ) {
				#	$yr += 100 if ( $yr < 30 ); # Arbitrary break point
				#	$yr += 1900;
				# }
				return sprintf('%4.4d-%2.2d-%2.2d', $yr, $mo, $da);
		}
	}
	return '0000-00-00';    # Undetermined date
}

sub getMoNo {
	my $mo = substr($_[0], 0, 3);
	$mo =~ tr/[A-Z]/[a-z]/;
	$mo = (index('janfebmaraprmayjunjulaugsepoctnovdec', $mo) / 3) + 1;
	if ( $mo == int($mo) && $mo > 0 ) {
		return $mo;
	} else {
		return 0;
	}
}

sub isLeapYear {
	my $yr = shift;
	if ( ((($yr % 4) == 0) && (($yr % 100) != 0)) || (($yr % 400) == 0) ) {
		return 1;
	} else {
		return 0;
	}
}