variant_add

    (PHP 5, PHP 7, PHP 8)

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

    说明

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

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

    Variant Addition Rules
    IfThen
    Both expressions are of the string typeConcatenation
    One expression is a string type and the other a characterAddition
    One expression is numeric and the other is a stringAddition
    Both expressions are numericAddition
    Either expression is NULLNULL is returned
    Both expressions are emptyInteger subtype is returned

    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

    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
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