Help needed urgently: Performing searches using regex

Question

Hello

 Can someone provide me with the format of how to do searches from a binary search tree of words using regex.

 

I created a program that stores the the words from a text file in a binary search tree. Now I have to be able to do various types of searches to return the words and the frequency of occurences.

 

e.g if I search for the word "deer"; or words that starts with "pr" or words that ends with "ed" etc . the program must be able to return the word/s and the number of times they occur.

 

I've tried following examples online but everything I"ve tried comes up with errors.

 

I am really new to this and it's posing a challenge for me.

 please help

Thanks You 

 

Here is the source code 

 

Using System;

using System.IO;

using System.Linq;

namespace binarysearchtree

{

class BinarySearchTree

{

static void Main(string[] args)

{

BinaryTree BT = new BinaryTree();

string line; // will be used to read the file, one line at a time

int count;

string[] words;

try

{

count = 1;

StreamReader reader = new StreamReader("testfile.txt");//create input stream

line = reader.ReadLine();//get the next line

while (line != null)

{

words = line.Split(' ');

for (int i = 0; i < words.Length; i++)

BT.Insert(words[i], count);

line = reader.ReadLine();

}

reader.Close();

}

catch (IOException e)

{

Console.WriteLine("" + e.ToString());

}

BT.Display();

Console.ReadLine();