How to call a C# Class from a C# Form

Question

This is my class:

using System;
using System.Collections.Generic;
using System.Text;

namespace Num2Wrd
{

public class NumberToEnglish
{

    public String changeNumericToWords(double numb)
    {
        String num = numb.ToString();
        return changeToWords(num, false);
    }

    public String changeCurrencyToWords(String numb)
    {
        return changeToWords(numb, true);
    }

    public String changeNumericToWords(String numb)
    {
        return changeToWords(numb, false);
    }

    public String changeCurrencyToWords(double numb)
    {
        return changeToWords(numb.ToString(), true);
    }

    private String changeToWords(String numb, bool isCurrency)
    {
        String val = "", wholeNo = numb, points = "", andStr = "", pointStr = "";
        String endStr = (isCurrency) ? ("Only") : ("");
        try
        {
            int decimalPlace = numb.IndexOf(".");
            if (decimalPlace > 0)
            {
                wholeNo = numb.Substring(0, decimalPlace);
                points = numb.Substring(decimalPlace + 1);
                if (Convert.ToInt32(points) > 0)
                {
                    andStr = (isCurrency) ? ("and") : ("point");// just to separate whole numbers from points/Rupees
                    endStr = (isCurrency) ? ("Rupees " + endStr) : ("");
                    pointStr = translateRupees(points);
                }
            }
            val = String.Format("{0} {1}{2} {3}", translateWholeNumber(wholeNo).Trim(), andStr, pointStr, endStr);
        }
        catch
        {
            ;
        }
        return val;
    }

    private String translateWholeNumber(String number)
    {
        string word = "";
        try
        {
            bool beginsZero = false;//tests for 0XX
            bool isDone = false;//test if already translated
            double dblAmt = (Convert.ToDouble(number));
            //if ((dblAmt > 0) && number.StartsWith("0"))

            if (dblAmt > 0)
            {//test for zero or digit zero in a nuemric
                beginsZero = number.StartsWith("0");
                int numDigits = number.Length;
                int pos = 0;//store digit grouping
                String place = "";//digit grouping name:hundres,thousand,etc...
                switch (numDigits)
                {
                    case 1://ones' range
                        word = ones(number);
                        isDone = true;
                        break;
                    case 2://tens' range
                        word = tens(number);
                        isDone = true;
                        break;
                    case 3://hundreds' range
                        pos = (numDigits % 3) + 1;
                        place = " Hundred ";
                        break;
                    case 4://thousands' range
                    case 5:
                    case 6:
                        pos = (numDigits % 4) + 1;
                        place = " Thousand ";
                        break;
                    case 7://millions' range
                    case 8:
                    case 9:
                        pos = (numDigits % 7) + 1;
                        place = " Million ";
                        break;
                    case 10://Billions's range
                        pos = (numDigits % 10) + 1;
                        place = " Billion ";
                        break;
                    //add extra case options for anything above Billion...
                    default:
                        isDone = true;
                        break;
                }
                if (!isDone)
                {//if transalation is not done, continue...(Recursion comes in now!!)
                    word = translateWholeNumber(number.Substring(0, pos)) + place + translateWholeNumber(number.Substring(pos));
                    //check for trailing zeros
                    if (beginsZero) word = " and " + word.Trim();
                }
                //ignore digit grouping names
                if (word.Trim().Equals(place.Trim())) word = "";
            }
        }
            catch
            {
                ;
            }
        return word.Trim();
    }

    private String tens(String digit)
    {
        int digt = Convert.ToInt32(digit);
        String name = null;
        switch (digt)
        {
            case 10:
                name = "Ten";
                break;
            case 11:
                name = "Eleven";
                break;
            case 12:
                name = "Twelve";
                break;
            case 13:
                name = "Thirteen";
                break;
            case 14:
                name = "Fourteen";
                break;
            case 15:
                name = "Fifteen";
                break;
            case 16:
                name = "Sixteen";
                break;
            case 17:
                name = "Seventeen";
                break;
            case 18:
                name = "Eighteen";
                break;
            case 19:
                name = "Nineteen";
                break;
            case 20:
                name = "Twenty";
                break;
            case 30:
                name = "Thirty";
                break;
            case 40:
                name = "Fourty";
                break;
            case 50:
                name = "Fifty";
                break;
            case 60:
                name = "Sixty";
                break;
            case 70:
                name = "Seventy";
                break;
            case 80:
                name = "Eighty";
                break;
            case 90:
                name = "Ninety";
                break;
            default:
                if (digt > 0)
                {
                    name = tens(digit.Substring(0, 1) + "0") + " " + ones(digit.Substring(1));
                }
                break;
        }
        return name;
    }

    private String ones(String digit)
    {
        int digt = Convert.ToInt32(digit);
        String name = "";
        switch (digt)
        {
            case 1:
                name = "One";
                break;
            case 2:
                name = "Two";
                break;
            case 3:
                name = "Three";
                break;
            case 4:
                name = "Four";
                break;
            case 5:
                name = "Five";
                break;
            case 6:
                name = "Six";
                break;
            case 7:
                name = "Seven";
                break;
            case 8:
                name = "Eight";
                break;
            case 9:
                name = "Nine";
                break;
        }
        return name;
    }

    private String translateRupees(String Rupees)
    {
        String cts = "", digit = "", engOne = "";
        for (int i = 0; i < Rupees.Length; i++)
        {
            digit = Rupees[i].ToString();
            if (digit.Equals("0"))
            {
                engOne = "Zero";
            }
            else
            {
                engOne = ones(digit);
            }
            cts += " " + engOne;
        }
        return cts;
    }
}
}

Form contains two Textboxes (textBox1 and textBox2) and a Button(button1). I want to type an amount in numbers in textBox1 and click on the button. The amount entered in numbers in textBox1 has to be converted to text and appear in textbox2. Functions to convert are in above C# class file. I am a new student. Can anyone help me in solving this problem.

Answer 1

 public partial class Form1 : Form
    {
        NumberToEnglish Obj = new NumberToEnglish();
        public Form1()
        {
            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)
        {
            textBox2.Text = Obj.changeCurrencyToWords(textBox1.Text);//As your method accept a string..
        }
    }

Answer 2

You have to create an object for 'NumberToEnglish' Class and use it in Form1.cs this way

 public partial class Form1 : Form
    {
        NumberToEnglish neObj = new NumberToEnglish();
        public Form1()
        {
            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)
        {
            textBox2.Text = neObj.changeCurrencyToWords(Convert.ToDouble(textBox1.Text));
        }
    }