Adds left to right using the following rules (taken from the MSDN library), which correspond to those of Visual Basic:
|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.
As with all the variant arithmetic functions, the parameters for this function can be either a PHP native type (integer, string, floating point, boolean or null), or an instance of a COM, VARIANT or DOTNET class. PHP native types will be converted to variants using the same rules as found in the constructor for the class. COM and DOTNET objects will have the value of their default property taken and used as the variant value.
The variant arithmetic functions are wrappers around the similarly named functions in the COM library; for more information on these functions, consult the MSDN library. The PHP functions are named slightly differently; for example variant_add in PHP corresponds to VarAdd() in the MSDN documentation.
Returns the result.
Exceptions and Errors
Throws a com_exception on failure.