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(PHP 5, PHP 7)

variant_add"Adds" two variant values together and returns the result


mixed variant_add ( mixed $left , mixed $right )

Adds left to right using the following rules (taken from the MSDN library), which correspond to those of Visual Basic:

Variant Addition Rules
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



The left operand.


The right operand.


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()


Returns the result.


  • variant_sub() - Subtracts the value of the right variant from the left variant value

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