import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.lang.String;
import java.lang.Integer;
public class jisuanqi extends Applet implements ActionListener
{ 
  static String xianshi;
  static float caozuoshu,jieguo;
  int biaoji,yunsuanfu,zhengfuhao;
  
  TextField text;
  Button n1,n2,n3,n4,n5,n6,n7,n8,n9,n0,point,minus,plus,subtract,multiply,divild,equal,back,ce;
  
  public void init()
  {
   xianshi=new String("");
   caozuoshu=0;
   jieguo=0;
   biaoji=-1;
   yunsuanfu=0;
   zhengfuhao=0;
   

   text=new TextField(11);
   text.setEditable(false);
   text.setText("");
   
   n1=new Button("1");
   n2=new Button("2");
   n3=new Button("3");
   n4=new Button("4");
   n5=new Button("5");
   n6=new Button("6");
   n7=new Button("7");
   n8=new Button("8");
   n9=new Button("9");
   n0=new Button("0");
   point=new Button(".");
   minus=new Button("-/+");
   plus=new Button("+");
   subtract=new Button("-");
   multiply=new Button("*");
   divild=new Button("/");
   equal=new Button("=");
   back=new Button("back");
   ce=new Button("ce");
   
   add(text);
   add(n1); 
   add(n2);
   add(n3);
   add(n4);
   add(n5);
   add(n6);
   add(n7);
   add(n8);
   add(n9);
   add(n0);
   add(point);
   add(minus);
   add(plus);
   add(subtract);
   add(multiply);
   add(divild);
   add(equal);
   add(back);
   add(ce);
   
   n1.addActionListener(this);
   n2.addActionListener(this);
   n3.addActionListener(this);
   n4.addActionListener(this);
   n5.addActionListener(this);
   n6.addActionListener(this);
   n7.addActionListener(this);
   n8.addActionListener(this);
   n9.addActionListener(this);
   n0.addActionListener(this);
   point.addActionListener(this);
   minus.addActionListener(this);
   plus.addActionListener(this);
   subtract.addActionListener(this);
   multiply.addActionListener(this);
   divild.addActionListener(this);
   equal.addActionListener(this);
   back.addActionListener(this);
   ce.addActionListener(this);
 
   } 
  

  public void actionPerformed(ActionEvent e)
  {
   if(e.getSource()==n1)
     {
      if(biaoji==1){xianshi="";biaoji=0;}
      xianshi=xianshi+"1";
      caozuoshu=Float.parseFloat(xianshi);
      if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
      text.setText(xianshi);
      }
   else if(e.getSource()==n2)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"2";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n3)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"3";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n4)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"4";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n5)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"5";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n6)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"6";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n7)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"7";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n8)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"8";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n9)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"9";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==n0)
          {
           if(biaoji==1){xianshi="";biaoji=0;}
           xianshi=xianshi+"0";
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==point)
          {if(biaoji==1){xianshi="";biaoji=0;}
           if(xianshi.indexOf('.')==-1)
             {xianshi=xianshi+".";}
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
           }
   else if(e.getSource()==minus)
          {if(biaoji==1){xianshi="";biaoji=0;}
           if(xianshi.indexOf('-')==-1)
             {xianshi="-"+xianshi;}
           else
             {xianshi=xianshi.substring(1,xianshi.length());}
           caozuoshu=Float.parseFloat(xianshi);
           if(biaoji==-1){jieguo=caozuoshu;biaoji=-1;}
           text.setText(xianshi);
          }
           
   else if(e.getSource()==plus)
          {caozuoshu=0;biaoji=1;yunsuanfu=1;
           }
   else if(e.getSource()==subtract)
          {caozuoshu=0;biaoji=1;yunsuanfu=2;
           
          }
   else if(e.getSource()==multiply)
          {
           caozuoshu=0;biaoji=1;yunsuanfu=3;
           }
   else if(e.getSource()==divild)
          {
           caozuoshu=0;biaoji=1;yunsuanfu=4;
           }
   else if(e.getSource()==equal)
          {if(yunsuanfu==1){jieguo=jieguo+caozuoshu;biaoji=1;text.setText(xianshi=String.valueOf(jieguo));}
           if(yunsuanfu==2){jieguo=jieguo-caozuoshu;biaoji=1;text.setText(xianshi=String.valueOf(jieguo));}
           if(yunsuanfu==3){jieguo=jieguo*caozuoshu;biaoji=1;text.setText(xianshi=String.valueOf(jieguo));}
           if(yunsuanfu==4){jieguo=jieguo/caozuoshu;biaoji=1;text.setText(xianshi=String.valueOf(jieguo));}      
           }
    
    else if(e.getSource()==back)
          { 
           xianshi=xianshi.substring(0,xianshi.length()-1);
           caozuoshu=Integer.parseFlaot(xianshi);
         
           text.setText(xianshi);}
    else if(e.getSource()==ce)
          {
           xianshi=new String("");
           caozuoshu=0;
           jieguo=0;
           biaoji=-1;
           yunsuanfu=0;
           text.setText(xianshi);}