Number to Currency Convertor

The attached Num2Cur.cs file converts number to currency up to 999,999,999,999.9999 i.e (999 billion).

using System;
using System.Windows.Forms;
using System.Drawing;
class frm1
{
TextBox txtNo;
Label lblDisplay,lblText;
Button cmdClick;
Form frmNo2Cur;
int Hun,Tho,Mil,Bil;
String[] Ones = new String[] {"","One","Two",
"Three","Four","Five","Six","Seven","Eight","Nine"};
public frm1()
{
frmNo2Cur=new Form();
cmdClick=new Button();
cmdClick.Text="Click";
cmdClick.Location =new Point(300,60);
frmNo2Cur.Controls.Add(cmdClick);
txtNo=new TextBox();
txtNo.Location =new Point(130,60);
txtNo.Width =150;
frmNo2Cur.Controls.Add(txtNo);
lblDisplay=new Label();
lblDisplay.Location =new Point(20,60);
lblDisplay.Text="Enter the Number";
frmNo2Cur.Controls.Add(lblDisplay);
lblText=new Label();
lblText.Location =new Point(10,100);
lblText.Width=500;
lblText.Height=500;
frmNo2Cur.Controls.Add(lblText);
cmdClick.Click += new EventHandler(cmdClick_Click);
frmNo2Cur.Width=550;
frmNo2Cur.Text="Number to Currency";
frmNo2Cur.ShowDialog();
}
void Divide(String strn1)
{
int n1=strn1.Length;
switch(n1)
{
case 1:
goto case 3;
case 2:
goto case 3;
case 3:
Hun=Int32.Parse(strn1);
break;
case 4:
goto case 6;
case 5:
goto case 6;
case 6:
Hun=Int32.Parse(strn1.Substring(n1-3,3));
Tho=Int32.Parse(strn1.Substring(0,n1-3));
break;
case 7:
goto case 9;
case 8:
goto case 9;
case 9:
Hun=Int32.Parse(strn1.Substring(n1-3,3));
Tho=Int32.Parse(strn1.Substring(n1-6,3));
Mil=Int32.Parse(strn1.Substring(0,n1-6));
break;
case 10:
goto case 12;
case 11:
goto case 12;
case 12:
Hun=Int32.Parse(strn1.Substring(n1-3,3));
Tho=Int32.Parse(strn1.Substring(n1-6,3));
Mil=Int32.Parse(strn1.Substring(n1-9,3));
Bil=Int32.Parse(strn1.Substring(0,n1-9));
break;
}
}
string SplitDigits(int n2,String mode)
{
String[] Teens=new String []
"Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eightteen","Nineteen"};
String[] Tys=new String[]{"","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
String strH="",strT="";
int hun1=0,ten1=0,one1=0;
hun1=n2 /100;
if(hun1>0)
{strH= Ones[hun1] + " Hundred ";}
else if (hun1==0)
{strH=Ones[hun1];}
ten1=n2 % 100;
if (ten1>9 && ten1<20)
{
strT=Teens[ten1 % 10];}
else if (ten1>=20 || ten1<10)
{
one1=ten1 % 10;
ten1=ten1/10;
if (one1==0)
{
strT=Tys[ten1];
}
else
{
strT= Tys[ten1]+ " " +Ones[one1] ;
}
}
return (strH+strT);
}
string SplitDigits(String n2)
{
String strFra="";
int cnt=0;
for (int i=0;i<n2.Length;i++)
{
cnt=Int32.Parse(n2.Substring(i,1));
if (cnt==0)
strFra+=" zero ";
strFra+=" " + Ones[cnt];
}
return strFra;
}
string GenerateString(String strTxt)
{
String Num=""; String Fra="";
String strHun="",strTho="",strMil="",strBil="",strFra="";
try
{
if ( strTxt.IndexOf(".")<0)
{
Num=strTxt;
}
else
{
Num=strTxt.Substring(0,strTxt.IndexOf("."));
Fra=strTxt.Substring(strTxt.IndexOf(".")+1);
}
if (Num!="")
{Divide(Num);}
if (Hun>0)
{strHun=SplitDigits(Hun,"N");}
if (Tho>0)
{strTho=SplitDigits(Tho,"N")+" Thousand and ";}
if (Mil>0)
{strMil=SplitDigits(Mil,"N")+" Million and ";}
if (Bil>0)
{strBil=SplitDigits(Bil,"N")+ " Billion and " ;}
if (Fra!="")
{strFra=" point " + SplitDigits(Fra);}
}
catch(FormatException)
{
MessageBox.Show("It is not a Number","Error");
strBil="";strMil="";strTho="";strHun="";strFra="";
}
catch(OverflowException)
{
MessageBox.Show("The number is too large or too small","Error");
}
return (strBil + strMil + strTho + strHun +strFra );
}
protected void cmdClick_Click(Object sender , EventArgs e)
{
lblText.Text=GenerateString(txtNo.Text);
}
public static void Main(string []s)
{
frm1 frm=new frm1();
}
}