.NET library to parse ECMA-376 number format strings and format values like Excel and other spreadsheet softwares.

If you want to include ExcelNumberFormat in your project, you can install it directly from NuGet

To install ExcelNumberFormat, run the following command in the Package Manager Console

PM> Install-Package ExcelNumberFormat

var format = new NumberFormat("#.##");
Console.WriteLine(format.Format(1234.56, CultureInfo.InvariantCulture));

• Parses and formats most custom number formats as expected: decimal, percent, thousands, exponential, fraction, currency, date/time, duration, text.
• Supports multiple sections with conditions.
• Formats values with relevant constants from CultureInfo.
• Supports DateTime, TimeSpan and numeric values for date and duration formats.
• Supports both 1900- and 1904-based numeric datetimes (Excel on Mac uses 1904-based dates).
• Targets net20 and netstandard1.0 for max compatibility.

The Format() method takes a value of type object as parameter. Internally, the value is cast or converted to a specific .NET type depending on the kind of number format:

In case of errors, Format() returns the value from CompatibleConvert.ToString().

CompatibleConvert.ToString() formats floats and doubles with explicit precision, or falls back to Convert.ToString() for any other types. ExcelDateTime.TryConvert() uses DateTimes as is, or converts numeric values to a DateTime with adjustments for legacy Excel behaviors.

• 'General' is formatted with .ToString() instead of Excel conventions.
• No errors: Invalid format strings and incompatible input values are formatted with .ToString().
• No color information.
• Variable width space is returned as regular space.
• Repeat-to-fill characters are printed once, not repeated.
• No alignment hinting.
• No date conditions.