Probably most dates you will get as input are strings. But the problem with strings is
that you can not be sure if the string is a real date. Therefor
Zend_Date has spent an own static function to check date strings.
Zend_Locale has an own function
getDate($date, $locale) which parses a date and returns the
proper and normalized date parts. A monthname for example will be recognised and
returned just a month number. But as Zend_Locale does not know
anything about dates because it is a normalizing and localizing class we have
integrated an own function isDate($date) which checks this.
isDate($date, $format, $locale) can take up to 3 parameters
and needs minimum one parameter. So what we need to verify a date is, of course, the
date itself as string. The second parameter can be the format which the date is
expected to have. If no format is given the standard date format from your locale is
used. For details about how formats should look like see the chapter about self defined formats.
The third parameter is also optional as the second parameter and can be used to give a locale. We need the locale to normalize monthnames and daynames. So with the third parameter we are able to recognise dates like '01.Jänner.2000' or '01.January.2000' depending on the given locale.
isDate() of course checks if a date does exist.
Zend_Date itself does not check a date. So it is possible to
create a date like '31.February.2000' with
Zend_Date because Zend_Date will
automatically correct the date and return the proper date. In our case
'03.March.2000'. isDate() on the
other side does this check and will return FALSE on
'31.February.2000' because it knows that this date is impossible.
Example 174. Checking Dates
<?php
// Checking dates
$date = '01.03.2000';
if (Zend_Date::isDate($date)) {
print "String $date is a date";
} else {
print "String $date is NO date";
}
// Checking localized dates
$date = '01 February 2000';
if (Zend_Date::isDate($date,'dd MMMM yyyy', 'en')) {
print "String $date is a date";
} else {
print "String $date is NO date";
}
// Checking impossible dates
$date = '30 February 2000';
if (Zend_Date::isDate($date,'dd MMMM yyyy', 'en')) {
print "String $date is a date";
} else {
print "String $date is NO date";
}