ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Desktop.Mapping Namespace / SelectionSet Class / Count Property

Count Property (SelectionSet)
Gets the total count of records in the SelectionSet.
Syntax
public int Count {get;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 3.0 or higher.
See Also