OOP Program-13

(13) Write a program for calculator to accept an expression as a string in which the operands and operator are separated by zero or more spaces. For ex: 3+4 and 3 + 4 are acceptable expressions.

Program Code:

 import java.util.Scanner;

public class OOP_13 

{

 public static void main(String[] args) 

 {

  Scanner input = new Scanner(System.in);

  System.out.print("Enter Equation : ");

  String str = input.nextLine();

  String a = str.replaceAll(" ","");

  

  if (a.length() < 3) {

   System.out.println(

    "Minimum 2 Opearator and 1 Opearand Required");

   System.exit(0);

  }

  int result = 0;

  int i = 0;

  while(a.charAt(i)!='+' && a.charAt(i)!='-' && a.charAt(i)!='*' && a.charAt(i)!='/')

  {

   i++;

  }

  switch (a.charAt(i)) {

   case '+' : 

    result = Integer.parseInt(a.substring(0,i))+Integer.parseInt(a.substring(i+1,a.length()));

    break;

   case '-' : 

    result = Integer.parseInt(a.substring(0,i))-Integer.parseInt(a.substring(i+1,a.length()));

    break;

   case '*' : 

    result = Integer.parseInt(a.substring(0,i))*Integer.parseInt(a.substring(i+1,a.length()));

    break;

   case '/' : 

    result = Integer.parseInt(a.substring(0,i))/Integer.parseInt(a.substring(i+1,a.length()));

    break;

  }

  System.out.println(a.substring(0,i) + ' ' + a.charAt(i) + ' ' + a.substring(i+1,a.length())

   + " = " + result);

 }

}

Output: