Assigns a string value and data type to the CXlOper
[C++]
const CXlOper& FromString(
   const char* psz
);
Value to be applied to the CXlOper.
This function assigns the value of psz to the CXlOper, 
            and sets the type of the CXlOper to be xltypeStr.
Header: xllplus.h