Excel Add-in Development in C/C++: Applications in ... - F9

14 Excel Add-in Development in C/C++Table 2.4 Case-insensitive string comparisonsFormula...="A"="a"="a">"Z"="Z">"["=CHAR(90)>CHAR(91)...evaluates to:TRUEFALSETRUETRUEApart from string case conversion, Excel does not convert operands for these operators.Table 2.5 shows some examples of the consequences:Table 2.5 Mixed-type comparisonsFormula......evaluates to:=123="123" FALSE=123>"121" FALSE=123"123" TRUE=TRUE ="TRUE"FALSE2.6.7 Conversion of single-cell referencesExcel will convert a single-cell reference to the value of the cell referred to, unless it isbeing passed to a function that expects a reference as its parameter rather than a value.(Later chapters go into detail on such functions, but a simple example is ROW(), whichextracts and returns the row number of a cell reference.) If an operator or function usingthe reference requires a different data type than that of the reference’s value, then Excelwill also attempt to convert to the required type. (See next section for more detail.) Forexample, if a cell contains the formula =SUM(A1,B1), with A1 containing the number 123and B2 the string "456", Excel will convert the reference A1 to the value of that cell, 123,and the reference B1 to the string "456" and then to the argument type expected by SUM(),the number 456, leading finally to a result of 579.2.6.8 Conversion of multi-cell range referencesSome functions will work equally well with single cell references and range references,for example, SUM(A1,B1,C1) gives the same result as SUM(A1:C1). In the latter case, theSUM() function converts the range A1:C1 to a mixed type array of values and then iteratesthrough that converting and summing values where possible. The work of handling therange argument is done within the code of the SUM() function.However, there are cases where Excel needs to convert a range argument before callinga function or applying an operator. Here the behaviour is a little more complex. Table 2.6shows how Excel copes with range arguments in combination with a simple arithmeticoperation, plus one in this case. (The strings in row 3 indicate the formulae entered in the