How to use c # To implement a simple calculator

The following code can be used as a reference for beginners of C #. There is no end to the technology. I hope the following code can serve as a reference.

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