/// <summary>
/// This function is a pre-order, DFS recursive traversal function
/// </summary>
/// <param name="person">Current person node</param>
/// <param name="descendantName">Requested person</param>
/// <returns>requested descendant</returns>
public Person GetDescendant(Person person, string descendantName)
{
// Always inspect person before calling recursion (this is true when we're on the requested person)
if (person.Name == descendantName) return person;
// Cycle thru descendants
foreach (Person p in person.Descendants) {
// Call recursion and capture return value
Person temp = GetDescendant(p, descendantName);
// Inspect return value (this is true when we have found the requested person and are propagating them up)
if (temp != null && temp.Name == descendantName) return temp;
}
// This will be reached once we reach the end of a branch w/o finding our person on that branch
// This return value will be skipped over in the above foreach loop, thus allowing our requested person to propagate to the intial call
return null;
}
/// <summary>
/// This method initates a recursive Depth-First-Search
/// </summary>
/// <param name="person">Person node</param>
/// <param name="descendantName">Requested person</param>
/// <returns>Person's Birthday property as string. If null, returns Null string object.</returns>
public string GetBirthMonth(Person person, string descendantName)
{
try
{
System.Globalization.DateTimeFormatInfo mfi = new System.Globalization.DateTimeFormatInfo();
// Find person using recursive function
return mfi.GetMonthName(GetDescendant(person, descendantName).Birthday.Month).ToString();
}
// If person is not in list of descendants, GetDescendant will return the empty string
catch (NullReferenceException e)
{
Trace.Write("\n\n" + e.Message + "\n" + e.StackTrace + "\n\n");
return "";
}
}