Question

I want to apply the % (percentage) number format using open XML C#

I have numeric value 3.6 that I want to display that number in excel as `3.6%.

How do I achieve that?

Answer 1

  WorkbookStylesPart sp = workbookPart.AddNewPart<WorkbookStylesPart>();

Create a stylesheet,

 sp.Stylesheet = new Stylesheet();

Create a numberingformat,

sp.Stylesheet.NumberingFormats = new NumberingFormats();
// #.##% is also Excel style index 1

NumberingFormat nf2decimal = new NumberingFormat();
nf2decimal.NumberFormatId = UInt32Value.FromUInt32(3453);
nf2decimal.FormatCode = StringValue.FromString("0.0%");
sp.Stylesheet.NumberingFormat.Append(nf2decimal);

Create a cell format and apply the numbering format id

cellFormat = new CellFormat();
cellFormat.FontId = 0;
cellFormat.FillId = 0;
cellFormat.BorderId = 0;
cellFormat.FormatId = 0;
cellFormat.NumberFormatId = nf2decimal.NumberFormatId;
cellFormat.ApplyNumberFormat = BooleanValue.FromBoolean(true);
cellFormat.ApplyFont = true;

//append cell format for cells of header row
sp.Stylesheet.CellFormats.AppendChild<CellFormat>(cellFormat);


//update font count 
sp.Stylesheet.CellFormats.Count = UInt32Value.FromUInt32((uint)sp.Stylesheet.CellFormats.ChildElements.Count);


//save the changes to the style sheet part   
sp.Stylesheet.Save();

and when you append the value to the cell have the following center code hereonversion and apply the style index
in my case i had three style index hence the 3 one was my percentage style index i.e 2 since the indexes start from 0

string val = Convert.ToString(Convert.ToDecimal(value)/100);
Cell cell = new Cell();
cell.DataType = new EnumValue<CellValues>(CellValues.Number);
cell.CellValue = new CellValue(val);
cell.StyleIndex = 2;
row.Append(cell);