Question

I create Pie Chart in VS 2008 C# Project using Microsoft Office Interop Excel.

The code is:

Excel.Chart xlChart = (Excel.Chart)xlWorkBook
        .Charts
        .Add(Type.Missing, Type.Missing, Type.Missing, Type.Missing);                

Excel.Range xlDataRange = xlWorkSheet
        .get_Range(xlWorkSheet.Cells[
                       nDataForDiagramRow - alToExcelInvestmentGroupNames.Count,
                       _nColumnsCount - 3
                   ],
                   xlWorkSheet.Cells[
                       nDataForDiagramRow - 1, 
                       _nColumnsCount - 2
                   ]);

xlChart.ChartType = Excel.XlChartType.xl3DPieExploded;
xlChart.Elevation = 60;
xlChart.Rotation = 130;

xlChart.SetSourceData(xlDataRange, Type.Missing);
xlChart.ApplyDataLabels(Excel.XlDataLabelsType.xlDataLabelsShowLabelAndPercent,
                        Type.Missing, Type.Missing, Type.Missing, Type.Missing,
                        Type.Missing, Type.Missing, Type.Missing, Type.Missing,
                        Type.Missing);

xlChart.Location(Excel.XlChartLocation.xlLocationAsObject, xlWorkSheet.Name);

With method xlChart.ApplyDataLabels I make Labels and Percentage visible, but Percentage is Rounded.

How to access the format of label to show fractional part of percentage?

Answer 1

I’ve founded the solution myself.
nLabel is int number of label in collection of labels in chart.

Excel.Series xlSeries = (Excel.Series)xlWorkBook.ActiveChart.SeriesCollection(1);

Excel.DataLabel dl = (Excel.DataLabel)xlSeries.DataLabels(nLabel);

dl.NumberFormat = "0.0%";