Use the Excel Export API to Create a Cell Formula

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This example demonstrates how to create cell formulas using three different methods.

Formula from Textual Representation

In this code, the exporter instance is created with the XlExport.CreateExporter method which also creates the formula parser. A worksheet contains a heading row and four rows populated with data. The last column in each data row contains a formula created by supplying a formula string to the IXlCell.SetFormula method.

// Create an exporter instance.
IXlExporter exporter = XlExport.CreateExporter(documentFormat, new XlFormulaParser());
// Create a new document.
using (IXlDocument document = exporter.CreateDocument(stream)) {
    document.Options.Culture = CultureInfo.CurrentCulture;
    // Create a worksheet.
    using (IXlSheet sheet = document.CreateSheet()) {
        // Create worksheet columns and set their widths.
        for (int i = 0; i < 4; i++) {
            using (IXlColumn column = sheet.CreateColumn()) {
                column.WidthInPixels = 80;
            }
        }
        // Generate data for the document.
        string[] header = new string[] { "Description", "QTY", "Price", "Amount" };
        string[] product = new string[] { "Camembert", "Gorgonzola", "Mascarpone", "Mozzarella" };
        int[] qty = new int[] { 12, 15, 25, 10 };
        double[] price = new double[] { 23.25, 15.50, 12.99, 8.95 };
        double discount = 0.2;
        // Create the header row.
        using (IXlRow row = sheet.CreateRow()) {
            for (int i = 0; i < 4; i++) {
                using (IXlCell cell = row.CreateCell()) {
                    cell.Value = header[i];
                }
            }
        }
        // Create data rows using string formulas.
        for (int i = 0; i < 4; i++) {
            using (IXlRow row = sheet.CreateRow()) {
                using (IXlCell cell = row.CreateCell()) {
                    cell.Value = product[i];
                }
                using (IXlCell cell = row.CreateCell()) {
                    cell.Value = qty[i];
                }
                using (IXlCell cell = row.CreateCell()) {
                    cell.Value = price[i];
                }
                using (IXlCell cell = row.CreateCell()) {
                    // Set the formula to calculate the amount 
                    // applying 20% quantity discount on orders more than 15 items. 
                    cell.SetFormula(String.Format("=IF(B{0}>15,C{0}*B{0}*(1-{1}),C{0}*B{0})", i + 2, discount));
                }
            }
        }

    }
}

Formula from Expression Elements

This code snippet creates an IXlFormulaParameter expression from a combination of constants, operators and functions. Constants are transformed into the IXlFormulaParameter objects with the XlFunc.Param method. Operators are static methods of the XlOper object and functions are static methods of the XlFunc object.

When an expression is created, the IXlCell.SetFormula method is used to enter expression into a worksheet cell as the cell formula.

// Create the total row using IXlFormulaParameter.
using (IXlRow row = sheet.CreateRow()) {
    row.SkipCells(2);
    using (IXlCell cell = row.CreateCell()) {
        cell.Value = "Total:";
        cell.ApplyFormatting(totalRowFormatting);
    }
    using (IXlCell cell = row.CreateCell()) {
        // Set the formula to calculate the total amount plus 10 handling fee.
        // =SUM($D$2:$D$5)+10
        IXlFormulaParameter const10 = XlFunc.Param(10);
        IXlFormulaParameter sumAmountFunction = XlFunc.Sum(XlCellRange.FromLTRB(cell.ColumnIndex, 1, cell.ColumnIndex, row.RowIndex - 1).AsAbsolute());
        cell.SetFormula(XlOper.Add(sumAmountFunction, const10));
        cell.ApplyFormatting(totalRowFormatting);
    }
}

Formula from Tokens

This code snippet show how to create an expression “from scratch” by adding formula tokens (aka PTGs, “parsed things”) to the XlExpression instance which is a List<T><DevExpress.Export.Xl.XlPtgBase,> list of tokens arranged in Reverse-Polish Notation order. Subsequently, the expression is passed to the IXlCell.SetFormula method to specify a cell formula.

// Create a formula using XlExpression.
using (IXlRow row = sheet.CreateRow()) {
    row.SkipCells(2);
    using (IXlCell cell = row.CreateCell()) {
        cell.Value = "Mean value:";
        cell.ApplyFormatting(totalRowFormatting);
    }
    using (IXlCell cell = row.CreateCell()) {
        // Set the formula to calculate the mean value.
        // =$D$6/4
        XlExpression expression = new XlExpression();
        expression.Add(new XlPtgRef(new XlCellPosition(cell.ColumnIndex, row.RowIndex - 1, XlPositionType.Absolute, XlPositionType.Absolute)));
        expression.Add(new XlPtgInt(row.RowIndex - 2));
        expression.Add(new XlPtgBinaryOperator(XlPtgTypeCode.Div));
        cell.SetFormula(expression);
        cell.ApplyFormatting(totalRowFormatting);
    }
}