Q. Java program to make a simple calculator using switch case.

Here you will find an algorithm and program in Java programming language to make a simple calculator. First let us understand what is calculator?

Explanation : A calculator is used to make mathematical calculations. In this program we will create a simple calculator that can perform an arithmetic operation (+, -, *, /).

Calculator Program Algorithm

START
Step 1 : Initialise the two numbers.
Step 2 : Ask the user to enter an option by giving six options.
Step 3 : After getting the option from the user write if conditions for every operation based on the option.
Step 4 : Perform the respective operation.
Step 5 : Print the result.
STOP

Java Program to Make a Simple Calculator

import java.util.Scanner;
public class LFC {
  public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);
    System.out.print("Enter two operands: ");
    // nextDouble() reads the next double from the keyboard
    double num1 = reader.nextDouble();
    double num2 = reader.nextDouble();
    System.out.print("Enter an operator (+, -, *, /):  ");
    char ch = reader.next().charAt(0);
    double res;
    switch(ch)
    {
      case '+':
        res = num1 + num2;
        break;
      case '-':
        res = num1 - num2;
        break;
      case '*':
        res = num1 * num2;
        break;
      case '/':
        res = num1 / num2;
        break;
      // operator doesn't match any case constant (+, -, *, /)
      default:
        System.out.printf("Error! operator is not correct");
        return;
    }
    System.out.printf("%.1f %c %.1f = %.1f", num1, ch, num2, res);
  }
}

Output

Enter an operator (+, -, *, /): *
Enter two operands: 8 6
8.0 * 6.0 = 48.0