The BTree class represents an ordered symbol table of generic key-value pairs. It supports the Put, Get, IndexerContains, Count, and IsEmpty methods.

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 B-tree. It requires that the key type implements the IComparable interface and calls the CompareTo() and method to compare two keys. It does not call either Equals() or GetHashCode(). The Get, Put, and Contains operations each make log_M(N) probes in the worst case, where N is the number of key-value pairs and M is the branching factor. The Count, and IsEmpty operations take constant time. Construction takes constant time.