public sealed class Subtype : ArcGIS.Core.CoreObjectsBase, System.IDisposable  

public string GetDomainStringFromField(Row row, Field field)
{
  // Get the table and table definition from the Row
  using (Table table = row.GetTable())
  using (TableDefinition tableDefinition = table.GetDefinition())
  {
    // Get name of subtype field
    string subtypeFieldName = tableDefinition.GetSubtypeField();

    // Get subtype, if any
    Subtype subtype = null;

    if (subtypeFieldName.Length != 0)
    {
      // Get value of subtype field for this row
      var varSubtypeCode = row[subtypeFieldName];
      long subtypeCode = (long)varSubtypeCode;

      // Get subtype for this row
      subtype = tableDefinition.GetSubtypes().First(x => x.GetCode() == subtypeCode);
    }

    // Get the coded value domain for this field
    CodedValueDomain domain = field.GetDomain(subtype) as CodedValueDomain;

    // Return the text string for this field
    if (domain != null)
    {
      return domain.GetName(row[field.Name]);
    }
    else
    {
      return row[field.Name].ToString();
    }
  }
}