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variant_sub

(PHP 5, PHP 7, PHP 8)

variant_sub — Subtracts 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