simple-calculator-java/SimpleCalculator_beta.java at main · voyager2005/simple-calculator-java · GitHub

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import java.util.Scanner;

public class SimpleCalculator
{
    boolean addition = false;
    boolean subtraction = false;
    boolean multlipication = false;
    boolean division = false;
    boolean squareRoot = false;
    boolean power = false;
    boolean remainder = false;

    double solution;

    String firstNumber = "";
    String secondNumber = "" ;
    String input = "" ;
    boolean whiteSpaceCounter = false;

    void compute(Scanner sc)
    {
        // accpeting value
        input = sc.nextLine().trim();

        for(int i = 0 ; i < input.length() ; i++)
        {
            char ch = input.charAt(i);

            if( Character.isDigit(ch) || ch == '.')
            {
                if(whiteSpaceCounter == false)
                {
                    firstNumber = firstNumber + ch ;
                }
                else if(whiteSpaceCounter == true)
                {
                    secondNumber = secondNumber + ch ;
                }
            }
            else
            {
                whiteSpaceCounter = true;

                if( ch == '+')
                    addition = true;
                else if( ch == '-')
                    subtraction = true;
                else if( ch == '*')
                    multlipication = true;
                else if( ch == '/')
                    division = true;
                else if(ch == '_')
                {
                    squareRoot = true;
                    squareRoot(firstNumber);
                }
                else if( ch == '^')
                    power = true;
                else if( ch == '%')
                    remainder = true;
            }
        }

        if(addition == true)
            addition(firstNumber, secondNumber);
        else if(subtraction == true)
            subtraction(firstNumber, secondNumber);
        else if(multlipication == true)
            multlipication(firstNumber, secondNumber);
        else if(division == true)
            division(firstNumber, secondNumber);
        else if(power == true)
            power(firstNumber, secondNumber);
        else if(remainder == true)
            remainder(firstNumber, secondNumber);
    }

    double addition( String a, String b)
    {
        double x = Double.parseDouble(a);
        double y = Double.parseDouble(b);

        solution = x + y ;

        return solution;
    }

    double subtraction( String a, String b)
    {
        double x = Double.parseDouble(a);
        double y = Double.parseDouble(b);

        solution = x - y;

        return solution;
    }

    double multlipication( String a, String b)
    {
        double x = Double.parseDouble(a);
        double y = Double.parseDouble(b);

        solution = x * y;

        return solution;
    }

    double division(String a, String b)
    {
        double x = Double.parseDouble(a);
        double y = Double.parseDouble(b);

        solution = x / y ;

        return solution;
    }

    double squareRoot(String a)
    {
        double x = Double.parseDouble(a);

        solution = Math.sqrt(x);

        return solution;
    }

    double power(String a, String b)
    {
        double x = Double.parseDouble(a);
        double y = Double.parseDouble(b);

        solution = Math.pow(x,y);

        return solution;
    }

    double remainder(String a, String b)
    {
        double x = Double.parseDouble(a);
        double y = Double.parseDouble(b);

        solution = x % y;

        return solution;
    }

    void display()
    {
        System.out.println(input + " = " + solution);
    }

    void initialize()
    {
        addition = false;
        subtraction = false;
        multlipication = false;
        division = false;
        squareRoot = false;
        power = false;
        remainder = false;

        solution = 0;

        firstNumber = "";
        secondNumber = "" ;
        whiteSpaceCounter = false;
    }

    public static void main(String args[])
    {
        //declaration
        Scanner sc = new Scanner(System.in);
        SimpleCalculator obj = new SimpleCalculator();
        int thread = 0 ;

        while(thread == 0)
        {
            System.out.print("Enter mathematical expression: ");
            obj.compute(sc);
            obj.display();
            obj.initialize();
        }
    }
}