array ( 0 => 'index.php', 1 => 'PHP Manual', ), 'head' => array ( 0 => 'UTF-8', 1 => 'zh', ), 'this' => array ( 0 => 'function.variant-sub.php', 1 => 'variant_sub', 2 => 'Subtracts the value of the right variant from the left variant value', ), 'up' => array ( 0 => 'ref.com.php', 1 => 'COM 函数', ), 'prev' => array ( 0 => 'function.variant-set-type.php', 1 => 'variant_set_type', ), 'next' => array ( 0 => 'function.variant-xor.php', 1 => 'variant_xor', ), 'alternatives' => array ( ), 'source' => array ( 'lang' => 'en', 'path' => 'reference/com/functions/variant-sub.xml', ), 'history' => array ( ), ); $setup["toc"] = $TOC; $setup["toc_deprecated"] = $TOC_DEPRECATED; $setup["parents"] = $PARENTS; manual_setup($setup); contributors($setup); ?>

variant_sub

(PHP 5, PHP 7, PHP 8)

variant_subSubtracts the value of the right variant from the left variant value

说明

variant_sub(mixed $left, mixed $right): variant

Subtracts right from left.

参数

left

The left operand.

right

The right operand.

注意:

对于所有变量运算函数,本函数的参数可以是 PHP 内置的类型(整数,字符串,浮点数,布尔型或者 null),或者是一个 COM,VARIANT 或者 DOTNET 类的实例。PHP 内置类型将会使用和构造variant类相同的规则转换成变量。COM 和 DOTNET 对象的值将会取其默认属性并被当成变量值使用。

变量运算函数是同名函数在 COM 库中的外包;有关此类函数的更多信息参见 MSDN 库。PHP 函数命名有少许区别,例如 PHP 中的 variant_add() 对应于 MSDN 文档中的 VarAdd()

返回值

Variant Subtraction Rules
If Then
Both expressions are of the string type Subtraction
One expression is a string type and the other a character Subtraction
One expression is numeric and the other is a string Subtraction.
Both expressions are numeric Subtraction
Either expression is NULL NULL is returned
Both expressions are empty Empty string is returned

错误/异常

Throws a com_exception on failure.

参见