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VARIANT class

(PHP 4 >= 4.1.0, PHP 5)

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.

$vVar = new VARIANT($var)

Methods

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 预定义常量. 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:

Example #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/>";
?>

Example #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.

Note:

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 printing 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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PHP手册 - N: VARIANT class

用户评论:

darren at dcook dot org (17-Jul-2007 01:59)

If you are frustrated that print_r($obj) (where $obj is something returned from a call to a function on a COM object) does not return anything helpful, and that variant_get_type($obj) just returns a number, the function you are actually after is:
  com_print_typeinfo($obj);

It lists all functions, variables, their types in a human-readable (well, programmer-readable) format. Lovely!

mark dot pearson at capita dot co dot uk (29-Oct-2003 07:51)

Running PHP 4.3.2 on Windows 2000 I had to use the following expression to create an empty Variant:

<?php
 $empty = new Variant(null);
 print $empty->type //     ==>   1
?>

NOT

<?php
 $empty = new Variant();
 print $empty->type //     ==>   0
?>

The two expressions return different Variant type values!

richard dot quadling at carval dot co dot uk (26-Feb-2003 01:50)

With thanks to Harald Radi and Wez Furlong.

Some VBA functions have optional parameters. Sometimes the parameters you want to pass are not consecutive.

e.g.

GoTo What:=wdGoToBookmark, Name="BookMarkName"
GoTo(wdGoToBookmark,,,"BookMarkName)

In PHP, the "blank" parameters need to be empty.

Which is ...

<?php
// Some servers may have an auto timeout, so take as long as you want.
set_time_limit(0);

// Show all errors, warnings and notices whilst developing.
error_reporting(E_ALL);

// Used as a placeholder in certain COM functions where no parameter is required.
$empty = new VARIANT();

// Load the appropriate type library.
com_load_typelib('Word.Application');

// Create an object to use.
$word = new COM('word.application') or die('Unable to load Word');
print "Loaded Word, version {$word->Version}\n";

// Open a new document with bookmarks of YourName and YourAge.
$word->Documents->Open('C:/Unfilled.DOC');

// Fill in the information from the form.
$word->Selection->GoTo(wdGoToBookmark,$empty,$empty,'YourName'); // Note use of wdGoToBookmark, from the typelibrary and the use of $empty.
$word->Selection->TypeText($_GET['YourName']);

$word->Selection->GoTo(wdGoToBookmark,$empty,$empty,'YourAge');
$word->Selection->TypeText($_GET['YourAge']);

// Save it, close word and finish.
$word->Documents[1]->SaveAs("C:/{$_GET['YourName']}.doc");
$word->Quit();
$word->Release();
$word = null;
print "Word closed.\n";
?>

The example document is ...

Hello [Bookmark of YourName], you are [Bookmark of YourAge] years old.

and it would be called ...

word.php?YourName=Richard%20Quadling&YourAge=35

Regards,

Richard.

alain at samoun dot com (02-Sep-2001 09:37)

<?php
# I think that we need some examples of this thing:
# Lets define a real variant:
$varREAL=  new Variant("9.34 is a real number",VT_R8);
print "Value:". $varREAL->value; # Will print 9.34
# Now an integer
  $varINT=  new Variant("9.34 Printed as an integer",VT_INT);
print "Value:". $varINT->value; # Will print 9
# Now a string
  $varSTR=  new Variant("9.34 Printed as a string",VT_BSTR);
print "Value:". $varSTR->value; # Will 9.34 Printed as a string
    
?>