Calculator In C#

using System;
 
using System.Windows.Forms;
 
using System.Drawing;
 
 
 
 
public class win:Form {
 
 
     Button[] b = new Button[10];
 
    Button bDot,bPlus,bSub,bMul,bDiv,bEqu,bClr;
 
    Panel panCalc;
 
    TextBox txtCalc;
 
    
 
    Double dblAcc;
 
    Double dblSec;
 
    bool blnClear,blnFrstOpen;
 
    String strOper;
 
    
 
    public win() {
 
       try {
 
        this.Text="Calculator";
 
        panCalc=new Panel();
 
        txtCalc = new TextBox();
 
 
         txtCalc.Location = new Point(10,10);
 
        txtCalc.Size=new Size(150,10);
 
        txtCalc.ReadOnly=true;
 
        txtCalc.RightToLeft=RightToLeft.Yes;
 
        panCalc.Size=new Size(200,200);
 
        panCalc.BackColor=Color.Aqua;
 
        panCalc.Controls.Add(txtCalc);
 
        addButtons(panCalc);
 
        this.Size=new Size(200,225);
 
        this.Controls.Add(panCalc);
 
        
 
        dblAcc=0;
 
        dblSec=0;
 
        blnFrstOpen=true;
 
        blnClear=false;
 
        strOper=new String('=',1);
 
        }
 
        catch (Exception e) {
 
        Console.WriteLine("error ...... " + e.StackTrace);
 
        }
 
    }
 
    
 
    private void addButtons(Panel p) {
 
        for (int i=0;i<=9;i++) {
 
            b[i]=new Button();
 
            b[i].Text=Convert.ToString(i);
 
            b[i].Size=new Size(25,25);
 
            b[i].BackColor=Color.White;
 
            b[i].Click+=new EventHandler(btn_clk);
 
            p.Controls.Add(b[i]);
 
        }
 
        b[0].Location=new Point(10,160);
 
        b[1].Location=new Point(10,120);
 
        b[4].Location=new Point(10,80);
 
        b[7].Location=new Point(10,40);
 
        
 
        b[2].Location=new Point(50,120);
 
        b[5].Location=new Point(50,80);
 
        b[8].Location=new Point(50,40);
 
        
 
        b[3].Location=new Point(90,120);
 
        b[6].Location=new Point(90,80);
 
        b[9].Location=new Point(90,40);
 
        
 
        bDot=new Button();
 
        bDot.Size=new Size(25,25);
 
        bDot.Location=new Point(50,160);
 
        bDot.BackColor=Color.White;
 
        bDot.Text=".";
 
        bDot.Click+=new EventHandler(btn_clk);
 
        
 
        bPlus=new Button();
 
        bPlus.Size=new Size(25,25);
 
        bPlus.Location=new Point(130,160);
 
        bPlus.BackColor=Color.White;
 
        bPlus.Text="+";
 
        bPlus.Click+=new EventHandler(btn_Oper);
 
        
 
        bSub=new Button();
 
        bSub.Size=new Size(25,25);
 
        bSub.Location=new Point(130,120);
 
        bSub.BackColor=Color.White;
 
        bSub.Text="-";
 
        bSub.Click+=new EventHandler(btn_Oper);
 
        
 
        bMul=new Button();
 
        bMul.Size=new Size(25,25);
 
        bMul.Location=new Point(130,80);
 
        bMul.BackColor=Color.White;
 
        bMul.Text="*";
 
        bMul.Click+=new EventHandler(btn_Oper);
 
        
 
        bDiv=new Button();
 
        bDiv.Size=new Size(25,25);
 
        bDiv.Location=new Point(130,40);
 
        bDiv.BackColor=Color.White;
 
        bDiv.Text="/";
 
        bDiv.Click+=new EventHandler(btn_Oper);
 
        
 
        bEqu=new Button();
 
        bEqu.Size=new Size(25,25);
 
        bEqu.Location=new Point(90,160);
 
        bEqu.BackColor=Color.White;
 
        bEqu.Text="=";
 
        bEqu.Click+=new EventHandler(btn_equ);
 
        
 
        bClr=new Button();
 
        bClr.Size=new Size(20,45);
 
        bClr.Location=new Point(170,40);
 
        bClr.BackColor=Color.Orange;
 
        bClr.Text="AC";
 
        bClr.Click+=new EventHandler(btn_clr);
 
 
         p.Controls.Add(bDot);
 
        p.Controls.Add(bPlus);
 
        p.Controls.Add(bSub);
 
        p.Controls.Add(bMul);
 
        p.Controls.Add(bDiv);
 
        p.Controls.Add(bEqu);
 
        p.Controls.Add(bClr);
 
    }
 
    
 
    private void btn_clk(object obj,EventArgs ea)
{
 
        if(blnClear)
 
            txtCalc.Text="";
 
        
 
        Button b3=(Button)obj;
 
        
 
        txtCalc.Text+=b3.Text;
 
        
 
        if (txtCalc.Text==".")
 
            txtCalc.Text="0.";
 
        dblSec=Convert.ToDouble(txtCalc.Text);
 
        
 
        blnClear=false;
 
    }
 
    
 
    private static void Main() {
 
        Application.Run(new win());
 
    }
 
    
 
    private void btn_Oper(object obj,EventArgs ea) {
 
        Button tmp=(Button)obj;
 
        strOper=tmp.Text;
 
        if (blnFrstOpen)
 
            dblAcc=dblSec;
 
        else
 
            calc();
 
 
         blnFrstOpen=false;
 
        blnClear=true;
 
    }
 
 
     private void btn_clr(object obj,EventArgs ea) {
 
        clear();
 
    }
 
 
     private void btn_equ(object obj,EventArgs ea) {
 
        calc();
 
        
 
    }
 
    
 
    private void calc() {
 
 
         switch(strOper) {
 
        
 
            case "+":
 
                dblAcc+=dblSec;
 
                break;
 
            case "-":
 
                dblAcc-=dblSec;
 
                break;
 
            case "*":
 
                dblAcc*=dblSec;
 
                break;
 
            case "/":
 
                dblAcc/=dblSec;
 
                break;
 
        }
 
    
 
        strOper="=";
 
        blnFrstOpen=true;
 
        txtCalc.Text=Convert.ToString(dblAcc);
 
        dblSec=dblAcc;
 
    }
 
    
 
    private void clear() {
 
        dblAcc=0;
 
        dblSec=0;
 
        blnFrstOpen=true;
 
        txtCalc.Text="";
 
        txtCalc.Focus();
 
 
     }
 
}