variant_add()
(PHP 5, PHP 7)
"Adds" two variant values together and returns the result
说明
variant_add(mixed $left, mixed $right): variant
Adds$leftto$rightusing the following rules(taken from the MSDN library), which correspond to those of Visual Basic:
If | Then |
---|---|
Both expressions are of the string type | Concatenation |
One expression is a string type and the other a character | Addition |
One expression is numeric and the other is a string | Addition |
Both expressions are numeric | Addition |
Either expression is NULL | NULL is returned |
Both expressions are empty | Integer subtype is returned |
参数
- $left
The left operand.
- $right
The right operand.
Note: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
Returns the result.
错误/异常
Throws a com_exception on failure.
参见
variant_sub()
Subtracts the value of the right variant from the left variant value