The BST class represents an ordered symbol table of generic key-value pairs. It supports the usual Put, Get, Indexer, Contains, Delete, Count, and IsEmpty methods. It also provides ordered methods for finding the Minimum, Maximum, Floor, and Ceiling. It also provides a Keys method for iterating over all of the keys. A symbol table implements the Associative array abstraction: when associating a value with a key that is already in the symbol table, the convention is to replace the old value with the new value. Unlike DictionaryTKey, TValue, this class uses the convention that values cannot be null. Setting the value associated with a key to null is equivalent to deleting the key from the symbol table.

This implementation uses a sorted array. It requires that the key type implements the IComparable interface and calls the CompareTo() method to compare two keys. It does not call either Equals() or GetHashCode(). The Put and Remove operations each take linear time in the worst case; the Contains, Ceiling, Floor, and Rank operations take logarithmic time; the Count, IsEmpty, Minimum, Maximum, and indexer operations take constant time. Construction takes constant time.