FormulaEngineer — A Highly Accurate Excel Formula Engine with support for 430+ Excel functions — explore the complete list NEW3.0.1

FormulaEngineer examples

Create, read, and style Excel workbooks in .NET.

Style workbooks as you write them — fonts, fills, borders, number formats, alignment, and layout — using ExcelStyledWriter. Every example below is a complete, runnable snippet.

Group
Example
6 examples in Conditional formatting

Icon set status indicators

EnableConditionalFormatting

Attaches traffic-light icons to a health-score column with explicit percentage thresholds, giving an at-a-glance status column that stays numeric underneath.

Write.cs
using FormulaEngineer.Api;
using FormulaEngineer.Api.Styling;

var stylingOptions =
    new ExcelStylingOptions
    {
        EnableConditionalFormatting = true
    };

using (var writer = new ExcelStyledWriter("icon-set-status-indicators.xlsx", null, stylingOptions))
{
    using (var sheet = writer.CreateWorksheet("Health"))
    {
        sheet.WriteRow("Service", "Health score");
        sheet.WriteRow("Formula API", 95);
        sheet.WriteRow("Import Worker", 70);
        sheet.WriteRow("Export Worker", 42);
        sheet.WriteRow("Dashboard Job", 88);

        sheet.AddConditionalFormat(
            "B2:B5",
            ExcelConditionalFormat.IconSet(
                ExcelIconSet.ThreeTrafficLights1,
                new[]
                {
                    ExcelConditionalFormatValue.Percent(0),
                    ExcelConditionalFormatValue.Percent(33),
                    ExcelConditionalFormatValue.Percent(67)
                }));
    }

    writer.Close();
}

Style your own workbooks

Styling is part of the same package — no separate install, no Excel, no COM automation.