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(PHP 5, PHP 7, PHP 8)
variant_sub — Subtracts the value of the right variant from the left variant value
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()
。
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 |
Throws a com_exception on failure.