(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:
對于所有變量運算函數，本函數的參數可以是 PHP 內置的類(lèi)型（整數，字符串，浮點(diǎn)數，布爾型或者
null），或者是一個(gè) COM，VARIANT 或者 DOTNET 類(lèi)的實(shí)例。PHP 內置類(lèi)型將會(huì )使用和構造variant類(lèi)相同的規則轉換成變量。COM 和 DOTNET 對象的值將會(huì )取其默認屬性并被當成變量值使用。變量運算函數是同名函數在 COM 庫中的外包；有關(guān)此類(lèi)函數的更多信息參見(jiàn) MSDN 庫。PHP 函數命名有少許區別，例如 PHP 中的 variant_add() 對應于 MSDN 文檔中的
VarAdd()。
Returns the result.
Throws a com_exception on failure.