PHP. Учебник. 2005

VARIANT

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VARIANT

(no version information, might be only in CVS)VARIANT -- VARIANT class

Синтаксис

$vVar = new VARIANT($var)

Description

- The VARIANT is COM's equivalent of the PHP zval; it is a structure that

can contain a value with a range of different possible types. The VARIANT

class provided by the COM extension allows you to have more control over

the way that PHP passes values to and from COM.

Methods

object VARIANT::VARIANT ([mixed value [, int type [, int codepage]]])

- VARIANT class constructor. Parameters:

value

- initial value. if omitted, or set to NULL an VT_EMPTY object is created.

type

- specifies the content type of the VARIANT object. Possible values are

one of the VT_XXX Разд. Предопределенные константы в Ссылка XII, COM and.Net (Windows).

- In PHP versions prior to PHP 5, you could force PHP to pass a variant

object by reference by OR'ing VT_BYREF

with the type. In PHP 5, this hack is not

supported; instead, PHP 5 can detect parameters passed by reference

automatically; they do not even need to be passed as VARIANT objects.

- Consult the MSDN library for additional information

on the VARIANT type.

codepage

- specifies the codepage that is used to convert strings to

unicode. See the parameter of the same name in the

COM class for more information.

- PHP versions prior to PHP 5 define a number of (undocumented) virtual properties

for instances of the VARIANT class; these properties have all been removed in

PHP 5 in favour of its more natural syntax; these differences are best

highlighted by example:

-

Пример 1. Variant example, PHP 4.x style

<?php

$v = new VARIANT(42);

print "The type is " . $v->type . "<br/>";

print "The value is " . $v->value . "<br/>";

?>

-

Пример 2. Variant example, PHP 5 style

<?php

$v = new VARIANT(42);

print "The type is " . variant_get_type($v). "<br/>";

print "The value is " . $v . "<br/>";

?>

- The reason for the change is that, internally, the COM extension sees

VARIANT, COM and DOTNET classes as the same thing, and the design

philosophy for these classes is that all property and member accesses are

passed through to COM with no interference. The new syntax is more

natural and less effort, and most of the removed virtual properties didn't

make any sense in a PHP context in any case.

Замечание:

PHP 5 takes a much simpler approach to handling VARIANTs; when returning

a value or fetching a variant property, the variant is converted to a PHP

value only when there is a direct mapping between the types that would

not result in a loss of information. In all other cases, the result is

returned as an instance of the VARIANT class. You can force PHP to

convert or evaluate the variant as a PHP native type by using a casting

operator explicitly, or implicitly casting to a string by

print()ing it. You may use the wide range of variant

functions to perform arithmetic operations on variants without forcing a

conversion or risking a loss of data.

- See also variant_get_type().

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