26.2. Creation of Measurements

In addition to integer data values, floating point types may be used, but "simple decimal fractions like 0.1 or 0.7 cannot be converted into their internal binary counterparts without a little loss of precision," sometimes giving surprising results. Also, do not compare two "float" type numbers for equality.

$measurement = 1234.7;
$unit = new Zend_Measure_Length((integer)$measurement, Zend_Measure_Length::STANDARD);
echo $unit;
// outputs '1234 m' (meters)

$unit = new Zend_Measure_Length($measurement, Zend_Measure_Length::STANDARD);
echo $unit;
// outputs '1234.7 m' (meters)

            

Many measurements received as input to ZF applications can only be passed to Zend_Measure_* classes as strings, such as numbers written using roman numerals or extremely large binary values that exceed the precision of PHP's native integer and float types. Since integers can be denoted using strings, if there is any risk of losing precision due to limitations of PHP's native integer and float types, using strings instead. Zend_Measure_Number uses the BCMath extension to support arbitrary precision, as shown in the example below, to avoid limitations in many PHP functions, such as bin2dec() .

$mystring = "10010100111010111010100001011011101010001";
$unit = new Zend_Measure_Number($mystring, Zend_Measure_Number::BINARY);

echo $unit;

            

Usually, Zend_Measure_* can automatically extract the desired measurement embedded in an arbitrary string. Only the first identifiable number denoted using standard European/Latin digits (0,1,2,3,4,5,6,7,8,9) will be used for measurement creation. If there are more numerals later in the string, the rest of these numerals will be ignored.

$mystring = "My house is 125m² in size";
$unit = new Zend_Measure_Area($mystring, Zend_Measure_Area::STANDARD);
echo $unit; // outputs "125 m²in size";

$mystring = "My house is 125m² in size, it has 5 rooms of 25m² each.";
$unit = new Zend_Measure_Area($mystring, Zend_Measure_Area::STANDARD);
echo $unit; // outputs "125 m² in size";

            

When a string is entered in a localized notation, the correct interpretation can not be determined without knowing the intended locale. The division of decimal digits with "." and grouping of thousands with "," is common in the English language, but not so in other languages. For example, the English number "1,234.50" would be interpreted as meaning "1.2345" in German. To deal with such problems, the locale-aware Zend_Measure_* family of classes offer the possibility to specify a language or region to disambiguate the input data and properly interpret the intended semantic value.

$locale = new Zend_Locale('de');
$mystring = "The boat is 1,234.50 long.";
$unit = new Zend_Measure_Length($mystring, Zend_Measure_Length::STANDARD, $locale);
echo $unit; // outputs "1.234 m"


$mystring = "The boat is 1,234.50 long.";
$unit = new Zend_Measure_Length($mystring, Zend_Measure_Length::STANDARD, 'en_US');
echo $unit; // outputs "1234.50 m"

            

Since Zend Framework 1.7.0 Zend_Measure does also support the usage of an application wide locale. You can simply set a Zend_Locale instance to the registry like shown below. With this notation you can forget about setting the locale manually with each instance when you want to use the same locale multiple times.

// in your bootstrap file
$locale = new Zend_Locale('de_AT');
Zend_Registry::set('Zend_Locale', $locale);

// somewhere in your application
$length = new Zend_Measure_Length(Zend_Measure_Length::METER();