Dictionary with multiple keys isn't working as expected

Question

I'm making a console program where I've got multiple values mapped to dictionary keyLookup. I'm using if commands that use the key to output some console.writeline = ("stuff"); but it only works if I have the value and the key the same (in the dictionary). I don't know why this is. I've been mucking about with list and foreach and some variables trying to figure out what I've done wrong but even though it continues to work how it works now it still doesn't work how I want.

Also if I have a word in my console.readline(); that isn't in my dictionary the whole thing crashes. Which I don't want, and I'm not sure of why its doing that either as at some point it didn't. Also my mathFunction dictionary works just how I want my keyLookup dictionary to work. Though I think the difference is in how I'm using a list to cross reference through keyLookup.

class MainClass
    {
        public static string Line;
        static string foundKey;
        public static void Main (string[] args)
        {
            while (true) 
            {
                if (Line == null)
                {Console.WriteLine ("Enter Input"); }
                WordChecker ();
            }
    }
    public static void WordChecker()
    {
        string inputString = Console.ReadLine ();
        inputString = inputString.ToLower();  

        string[] stripChars = { ";", ",", ".", "-", "_", "^", "(", ")", "[", "]",
            "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "\n", "\t", "\r" };

        foreach (string character in stripChars)
        {
            inputString = inputString.Replace(character, "");
        }
        // Split on spaces into a List of strings
        List<string> wordList = inputString.Split(' ').ToList();
        // Define and remove stopwords
        string[] stopwords = new string[] { "and", "the", "she", "for", "this", "you", "but" };

        foreach (string word in stopwords)
        {
            // While there's still an instance of a stopword in the wordList, remove it.
            // If we don't use a while loop on this each call to Remove simply removes a single
            // instance of the stopword from our wordList, and we can't call Replace on the
            // entire string (as opposed to the individual words in the string) as it's
            // too indiscriminate (i.e. removing 'and' will turn words like 'bandage' into 'bdage'!)
            while ( wordList.Contains(word) )
            {
                wordList.Remove(word);
            }
        }
        // Create a new Dictionary object
        Dictionary<string, int> dictionary = new Dictionary<string, int>();

        // Loop over all over the words in our wordList...

        foreach (string word in wordList)
        {
            // If the length of the word is at least three letters...

            if (word.Length >= 3) 
            {

                // ...check if the dictionary already has the word.

                if ( dictionary.ContainsKey(word) )
                {

                    // If we already have the word in the dictionary, increment the count of how many times it appears

                    dictionary[word]++;
                }
                else
                {
                    // Otherwise, if it's a new word then add it to the dictionary with an initial count of 1

                    dictionary[word] = 1;
                }
            }

            List<string> dicList = new List<string>();
            dicList = dictionary.Keys.ToList ();

            Dictionary<string, string> keyLookup = new Dictionary<string, string>();

            keyLookup["hey"] = "greeting";
            keyLookup["hi"] = "greeting";
            keyLookup["greeting"] = "greeting";
            keyLookup["math"] = "math";
            keyLookup["calculate"] = "math";
            keyLookup["equation"] = "math";

            foundKey = keyLookup[word];

            List<string> keyList = new List<string>();

            foreach (string keyWord in dicList)
            {
                if(keyWord == foundKey)
                {keyList.Add (keyWord); }
            }

            foreach (string mKey in keyList)
            {
            if(mKey == "greeting")
            {Greetings ();}

            if (mKey == "math") 
            {Math ();}
            }
        }
    }

    public static void Math()
    {
        Console.WriteLine ("What do you want me to math?");
        Console.WriteLine ("input a number");
        string input = Console.ReadLine ();

        decimal a = Convert.ToDecimal (input);
        Console.WriteLine("Tell me math function");
        string mFunction = Console.ReadLine();

        Console.WriteLine ("tell me another number");
        string inputB = Console.ReadLine();
        decimal b = Convert.ToDecimal (inputB);

        Dictionary<string, string> mathFunction = new Dictionary<string, string>();

        mathFunction["multiply"] = "multiply";
        mathFunction["times"] = "multiply";
        mathFunction["x"] = "multiply";
        mathFunction["*"] = "multiply";
        mathFunction["divide"] = "divide";
        mathFunction["/"] = "divide";
        mathFunction["subtract"] = "subtract";
        mathFunction["minus"] = "subtract";
        mathFunction["-"] = "subtract";
        mathFunction["add"] = "add";
        mathFunction["+"] = "add";
        mathFunction["plus"] = "add";

        string foundKey = mathFunction[mFunction];

        if (foundKey == "add")
        {
            Console.WriteLine (a + b);
        }
        else if (foundKey == "subtract")
        {
            Console.WriteLine (a - b);
        }
        else if (foundKey == "multiply")
        {
            Console.WriteLine (a * b);
        }
        else if (foundKey == "divide")
        {
            Console.WriteLine (a / b);
        }
        else
        {
            Console.WriteLine ("not a math");
        }
    }

    public static void Greetings()
    {
        Console.WriteLine("You said hello");
    }
}'

Answer 1

You should iterate through the dictionary differently (Dont use ToList-Function).

Try this instead:

foreach (KeyValuePair kvp (Of String, String) In testDictionary)
{
  Debug.WriteLine("Key:" + kvp.Key + " Value:" + kvp.Value);
}

And your application is crashing if the word doesn't match, because of this code (You're not creating a new entry that way):

// Otherwise, if it's a new word then add it to the dictionary with an initial count of 1
dictionary[word] = 1;

EDIT: I was wrong about that dictionary[word] = 1 would not create a new element. It's perfectly fine like this.

Answer 2

foundKey = keyLookup[word];

If word doesn't exist in keyLookup then it will crash.

string foundKey = mathFunction[mFunction];

if mFunction doesn't exist in mathFunction then it will crash.

---

If you're trying to make this a "conversational" program, then the word look-up is the most important part. You don't use predicates or LINQ, both can make string functions extremely easy. Currently you use a Dictionary. Why not use Lists for each keyword?

List<string> GreetingKeywords;
GreetingKeywords.Add("hello"); // ...

List<string> MathKeywords;
MathKeywords.Add("math"); // ...

foreach (var word in dicList)
{
  if (GreetingKeywords.Contains(word))
    { Greetings(); }
  if (MathKeywords.Contains(word))
    { Maths(); }
}

I'd suggest you read up on predicate and List/Dictionary functions such as Find, IndexOf, etc. etc. That knowledge is invaluable to C#.