(PHP 5, PHP 7, PHP 8)
variant_add — "Adds" two variant values together and returns the result
Adds left to right using
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 |
leftThe left operand.
rightThe right operand.
注意:
對于所有變量運(yùn)算函數(shù)，本函數(shù)的參數(shù)可以是 PHP 內(nèi)置的類型（整數(shù)，字符串，浮點(diǎn)數(shù)，布爾型或者
null），或者是一個(gè) COM，VARIANT 或者 DOTNET 類的實(shí)例。PHP 內(nèi)置類型將會使用和構(gòu)造variant類相同的規(guī)則轉(zhuǎn)換成變量。COM 和 DOTNET 對象的值將會取其默認(rèn)屬性并被當(dāng)成變量值使用。變量運(yùn)算函數(shù)是同名函數(shù)在 COM 庫中的外包；有關(guān)此類函數(shù)的更多信息參見 MSDN 庫。PHP 函數(shù)命名有少許區(qū)別，例如 PHP 中的 variant_add() 對應(yīng)于 MSDN 文檔中的
VarAdd()。
Returns the result.
Throws a com_exception on failure.