EVALUATE POSTFIX NOTATION

import java.io.*;

class PostFix

{

 public static void main(String args[])throws IOException

 {

  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

  System.out.println("ENTER ARRAY SIZE");

  int n=Integer.parseInt(br.readLine());

  int st[]=new int[n];

  int ch,top=-1,res=0;

  do

  {

    System.out.println("ENTER YOUR CHOICE");

    System.out.println("1:OPERAND 2: OPERATOR");

    ch = Integer.parseInt(br.readLine());

    switch(ch)

    {

       case 1:

       System.out.println("ENTER OPERAND");

      st[++top]= Integer.parseInt(br.readLine());

      break;

      case 2:

      System.out.println("ENTER OPERATOR");

      String s=br.readLine();

      char op=s.charAt(0);

     int a=st[top--];

     int b=st[top--];

     switch(op)

     {

      case '+':

      res=b+a;

     break;

     case '-':

     res=b-a;

     break;

     case '*':

     res=b*a;

     break;

    case '/':

    res=b/a;

    break;

    case '%':                                                                                                                                                    res=b%a;

     break;

   }

  st[++top]=res;

  System.out.println("result="+res);

  break;

  }

  }while(ch<=3);

  }

  }

                                                                                   

OUTPUT:

                                               

ENTER ARRAY SIZE

5

ENTER YOUR CHOICE

1:OPERAND 2: OPERATOR

1

ENTER OPERAND

5

ENTER YOUR CHOICE

1:OPERAND 2: OPERATOR

1

ENTER OPERAND

6

ENTER YOUR CHOICE

1:OPERAND 2: OPERATOR

1

ENTER OPERAND

2

ENTER YOUR CHOICE

1:OPERAND 2: OPERATOR

2

ENTER OPERATOR

+

result=8

ENTER YOUR CHOICE

1:OPERAND 2: OPERATOR

2

ENTER OPERATOR

*

result=40

ENTER YOUR CHOICE

1:OPERAND 2: OPERATOR