Parsing and normalization of input, combined with output to localized notations makes data accessible to users
in different locales. Many additional methods exist in Zend_Measure_* components to manipulate and
work with this data, after it has been normalized.
Probably the most important feature is the conversion into different units of measurement. The conversion of
a unit can be done any number of times using the method convertTo(). Units of measurement can
only be converted to other units of the same type (class). Therefore, it is not possible to convert (e.g.) a
length into a weight, which would might encourage poor programming practices and allow errors to propagate
without exceptions.
The convertTo method accepts an optional parameter. With this parameter you can define
an precision for the returned output. The standard precision is '2'.
例 32.10. Convert
$locale = new Zend_Locale('de');
$mystring = "1.234.567,89";
$unit = new Zend_Measure_Weight($mystring,'POND', $locale);
print "Kilo:".$unit->convertTo('KILOGRAM');
// constants are considered "better practice" than strings
print "Ton:".$unit->convertTo(Zend_Measure_Weight::TON);
// define a precision for the output
print "Ton:".$unit->convertTo(Zend_Measure_Weight::TON, 3);
Measurements can be added together using add() and subtracted using sub(). Each
addition will create a new object for the result. The actual object will never be changed by the class. The
new object will be of the same type as the originating object. Dynamic objects support a fluid style of
programming, where complex sequences of operations can be nested without risk of side-effects altering the
input objects.
例 32.11. Adding units
// Define objects
$unit = new Zend_Measure_Length(200, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
// Add $unit2 to $unit
$sum = $unit->add($unit2);
echo $sum; // outputs "300 cm"
![[注意]](images/note.png) |
Automatic conversion |
|---|---|
Adding one object to another will automatically convert it to the correct unit. It is not necessary to
call
|
例 32.12. Subtract
Subtraction of measurements works just like addition.
// Define objects
$unit = new Zend_Measure_Length(200, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
// Subtract $unit2 from $unit
$sum = $unit->sub($unit2);
echo $sum;
Measurements can also be compared, but without automatic unit conversion. Thus, equals()
returns TRUE, only if both the value and the unit of measure are identical.
例 32.13. Different measurements
// Define measurements
$unit = new Zend_Measure_Length(100, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
if ($unit->equals($unit2)) {
print "Both measurements are identical";
} else {
print "These are different measurements";
}
例 32.14. Identical measurements
// Define measurements
$unit = new Zend_Measure_Length(100, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
$unit2->setType(Zend_Measure_Length::CENTIMETER);
if ($unit->equals($unit2)) {
print "Both measurements are identical";
} else {
print "These are different measurements";
}
To determine if a measurement is less than or greater than another, use compare(), which
returns 0, -1 or 1 depending on the difference between the two objects. Identical measurements will return
0. Lesser ones will return a negative, greater ones a positive value.
例 32.15. Difference
$unit = new Zend_Measure_Length(100, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
$unit3 = new Zend_Measure_Length(1.2, Zend_Measure_Length::METER);
print "Equal:".$unit2->compare($unit);
print "Lesser:".$unit2->compare($unit3);
print "Greater:".$unit3->compare($unit2);
To change the value of a measurement explicitly, use setValue(). to overwrite the current
value. The parameters are the same as the constructor.
例 32.16. Changing a value
$locale = new Zend_Locale('de_AT');
$unit = new Zend_Measure_Length(1,Zend_Measure_Length::METER);
$unit->setValue(1.2);
echo $unit;
$unit->setValue(1.2, Zend_Measure_Length::KILOMETER);
echo $unit;
$unit->setValue("1.234,56", Zend_Measure_Length::MILLIMETER,$locale);
echo $unit;