When creating a measurement object, Zend_Measure
methods expect the input/original value as the
first parameter. This can be a
numeric argument
, a
string
without units, or a
localized string
with unit(s) specified.
. The second parameter defines the type of the measurement. Both parameters are mandatory. As an optional third
parameter, the language can be defined.
Exemple 18.2. Creation using integer variables
<?php require_once 'Zend.php'; Zend::loadClass('Zend_Measure'); $integer = 1234; $unit = new Zend_Measure($integer,Zend_Measure::LENGTH); echo $unit; // outputs '1234 m' ?>
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Using floating point |
---|---|
Instead of integer types, 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. |
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()
.
Exemple 18.3. Creation using strings
<?php require_once 'Zend.php'; Zend::loadClass('Zend_Measure'); Zend::loadClass('Zend_Measure_Number'); $mystring = "10010100111010111010100001011011101010001"; $unit = new Zend_Measure($mystring,Zend_Measure_Number::BINARY); echo $unit; ?>
Measurements can also be just a part of an arbitrary string. Usually, Zend_Measure
can
automatically extract the desired measurement. Only the first identifiable number will be used for
measurement creation. If there are more numbers in the string, the rest will be ignored.
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.