Roman Numeral Convertor
By Pavel Tsekov

Standard - to - Roman numeral convertor. This is a form that converts
standard-number input to roman numeral representation.

// project created on 08.10.2001 at 13:29
// standard(arabic) to roman numbers convertor 
//Author : Pavel Tsekov
// This project converts standard(arabic) numbers like : 1,2,3,4,.....,100,101,....260,...
// to roman numbers like : I, II, III, IV, V , ...... XCI,.......
using System;
using System.Windows.Forms;
using System.Drawing;
using System.Text;
class MainForm : Form
{
 private Button btnOK;
 private Label lblArabic;
 private Label lblRoman;
 private TextBox txtArabic;
 private TextBox txtRoman;
 public MainForm()
 {
  //form settings 
  this.MinimizeBox=false;
  this.MaximizeBox=false;
  this.FormBorderStyle=FormBorderStyle.Fixed3D;
  this.StartPosition=FormStartPosition.CenterScreen;
  this.Text = "Standard to Roman numbers";
  this.BackColor=Color.FromArgb(50,200,220);
  //label lblArabic settings
  lblArabic=new Label();
  lblArabic.Text="some number here (1 to 5000)";
  lblArabic.Font=new Font(lblArabic.Font,FontStyle.Bold);
  lblArabic.Left=0;
  lblArabic.Top=30;
  lblArabic.Width=this.ClientRectangle.Width;
  lblArabic.TextAlign=ContentAlignment.MiddleCenter;
  lblArabic.Visible=true;
  this.Controls.Add(lblArabic);
  //textbox txtArabic settings
  txtArabic=new TextBox();
  txtArabic.Width=40;
  txtArabic.Left=(this.ClientRectangle.Width-txtArabic.Width)/2;
  txtArabic.Top=60;
  txtArabic.Font=new Font(txtArabic.Font,FontStyle.Bold);
  txtArabic.BorderStyle=System.Windows.Forms.BorderStyle.FixedSingle;
  txtArabic.MaxLength=4;
  txtArabic.KeyPress+=new KeyPressEventHandler(txtArabic_KeyPress);
  txtArabic.Visible=true;
  this.Controls.Add(txtArabic);
  //label lblRoman settings
  lblRoman=new Label();
  lblRoman.Text="roman  representation";
  lblRoman.Font=new Font(lblArabic.Font,FontStyle.Bold);
  lblRoman.Left=0;
  lblRoman.Top=100;
  lblRoman.Width=this.ClientRectangle.Width;
  lblRoman.TextAlign=ContentAlignment.MiddleCenter;
  lblRoman.Visible=true;
  this.Controls.Add(lblRoman);
  //textbox txtRoman settings
  txtRoman=new TextBox();
  txtRoman.Width=120;
  txtRoman.Left=(this.ClientRectangle.Width-txtRoman.Width)/2;
  txtRoman.Top=130;
  txtRoman.Font=new Font(txtRoman.Font,FontStyle.Bold);
  txtRoman.BorderStyle=System.Windows.Forms.BorderStyle.FixedSingle;
  txtRoman.ReadOnly=true;
  txtRoman.Visible=true;
  this.Controls.Add(txtRoman);
  //button btnOK settings
  btnOK=new Button();
  btnOK.Text="Close";
  btnOK.FlatStyle=FlatStyle.Flat;
  btnOK.Left=this.ClientRectangle.Width-btnOK.Width-10;
  btnOK.Top=this.ClientRectangle.Height-btnOK.Height-10;
  btnOK.Visible=true;
  //tie the KeyPress event of the button to procedure : btnOK_Click
  btnOK.Click+=new EventHandler(btnOK_Click);
  this.Controls.Add(btnOK);
 }
 protected void txtArabic_KeyPress(object sender, KeyPressEventArgs eArgs)
 {
  switch(eArgs.KeyChar)
  {
   case '0':
   case '1':    
   case '2':
   case '3':
   case '4':
   case '5':
   case '6':
   case '7':
   case '8':
   case '9':
   //backspace
   case '\b': 
    //Handled = false -> that means that we say so Windows : "I haven't handled this event
    // so you must handle it." So in this case (if we press the keys '0','1',...,'9' or BackSpace
    // Windows will handle this event and as usually will add the symbol to the Text property of the
    // txtArabic textbox
    eArgs.Handled=false;
    if (eArgs.KeyChar=='\b')
     {
      if (txtArabic.Text.Length-1>0) txtRoman.Text=CalculateRoman(txtArabic.Text.Substring(0,txtArabic.Text.Length-1));
      else txtRoman.Text="Nothing";
     }
    else
     {
      txtRoman.Text=CalculateRoman(txtArabic.Text+eArgs.KeyChar);
     }
    break;
   default:
    //in all other cases we say that Handled=true. That means that we say to Windows:
    //"DO NOT handle this event, I've already handled it!". So here Windows won't add the sybmol
    // to the txtArabic.Text property (as if no key is pressed)
    eArgs.Handled=true;
    break;
  }
 }
 protected void btnOK_Click(object sender, EventArgs eArgs)
 {
  this.Close();
 }
 private string CalculateRoman(string strArabic)
 {
  int intArabic;
  if (strArabic=="") return("Nothing");
  try
  {
   intArabic=Convert.ToInt32(strArabic);
   StringBuilder retval=new StringBuilder();
   if (intArabic<1 || intArabic>5000) 
    {
     return("Arabic out of range!");
    }
   else
    {
     retval.Append(GenerateNumber(ref intArabic,1000,'M'));
     retval.Append(GenerateNumber(ref intArabic,500,'D'));
     retval.Append(GenerateNumber(ref intArabic,100,'C'));
     retval.Append(GenerateNumber(ref intArabic,50,'L'));
     retval.Append(GenerateNumber(ref intArabic,10,'X'));
     retval.Append(GenerateNumber(ref intArabic,5,'V'));
     retval.Append(GenerateNumber(ref intArabic,1,'I'));
     //let's replace the some substrings like:
     //IIII to IV, VIV to IX, etc.
     retval.Replace("IIII","IV");
     retval.Replace("VIV","IX");
     retval.Replace("XXXX","XL");
     retval.Replace("LXL","XC");
     retval.Replace("CCCC","CD");
     retval.Replace("DCD","CM");
     return(retval.ToString());

    }  
  }
  catch (Exception e)
  {
   MessageBox.Show(e.Message);
   return("Arabic number not correct!");
  }
 }
 private string GenerateNumber(ref int value, int magnitude, char letter)
 {
  StringBuilder numberstring=new StringBuilder();
  while (value>=magnitude)
   {
    value-=magnitude;
    numberstring.Append(letter);
   }
  return(numberstring.ToString());
 }
 public static void Main(string[] args)
 {
  Application.Run(new MainForm());
 }
}