/// <summary> Adds a profCourse to this network.
/// If the profCourse is already in the nework, this invocation has no effect.
/// </summary>
/// <param name="pc">the profCourse to be added
/// </param>
/// <returns> the variable itself
/// </returns>
/// <throws> NullPointerException if <tt>v</tt> is <tt>null</tt> </throws>
/// <throws> IllegalArgumentException if <tt>v</tt> is already added to another network </throws>
protected internal virtual Professor Add(Professor pc)
{
if (!professors.Contains(pc))
{
if (pc.Index >= 0)
{
throw new ArgumentException();
}
pc.Index = professors.Count;
professors.Add(pc);
}
return pc;
}
protected internal static String ToString(Professor[] pc)
{
String s = "";
if (pc != null)
{
String delim = "";
for (int i = 0; i < pc.Length; i++)
{
s += (delim + pc[i]);
delim = ",";
}
}
return "{" + s + "}";
}
