CODEWITHSUNDEEP
javaboolean
user2826974
user2826974

Reputation: 199

detect Consecutive number using boolean

public class ConsecutiveChecker
{
     public static void main( String[] args )
    { 
    java.util.Scanner keyboardReader = new java.util.Scanner(System.in);
    int number = keyboardReader.nextInt();

    int w;
    int x;
    int y;
    int z;
    // w= fourth digit, x= third digit, y= second digit, z= first digit
    w = (number - (number % 1000)) / 1000;
    x = ((number - (number % 100)) % 1000) / 10;
    y = ((number - (number % 10)) % 100) * 10;
    z = (1000)*(number % 10);

    boolean isOneDigitConsecutive;
    isOneDigitConsecutive = (number <= 9);

    boolean isTwoDigitConsecutive;
    isTwoDigitConsecutive = (w = 0) && (x = 0) && (y <= 9) && (y - z ==1);

    boolean isConsecutive = (isOneDigitConsecutive || isTwoDigitConsecutive || isThreeDigitConsecutive || isFourDigitConsecutive)
    System.out.println(); 
}

}

Hi, I'm new to Java and I have to write a code that detects whether a 4 digit number(user entered) is consecutive or not using boolean variable. Consecutive as in 0543, 1234, 0009, 0034(a single digit counts as consecutive). I've written this part of code until now, the problem is I don't understand why is my line
boolean isTwoDigitConsecutive; isTwoDigitConsecutive = (w = 0) && (x = 0) && (y <= 9) && (y - z ==1); wrong. it says that i can't use && with Int.

I would like to have some clarifications on how to use boolean variable.

Thank you in advance.

*edit: Thank you for your help, I listened to your advice and changed my code accordingly.

Upvotes: 0

Views: 914

Answers (4)

Elist
Elist

Reputation: 5533

In addition to everything said here, your code can be cleaner and more efficient.

  • Perform the "consecutiveness" test inside a separate method. It is nicer and can be reused later in the code.
  • Always use loops, arrays and other tools to avoid repeating similar code when possible. In this case, you basically want to test each two descendant digits one against the other, so do it in a loop.
  • It's always good to check the output, catch (and prompt) exceptions, and comment the code.

    public class ConsecutiveChecker {
    /**
     * return true if number digits are consecutively increasing.
     *
     * @param num
     * @return
     */
    private static boolean isConsecutive(int num) {
        if(num < 0 || num > 9999) throw new RuntimeException("Input out of range (0-9999)");
        // We check if the digits are downward consecutive from right to left
        // (which is same as upward consecutive from left to right, but easier
        // and more efficient to compute).
        while (num > 0) {
            int leftDigit = num%10;
            int secondFromLeftDigit = (num/10)%10;
            if (leftDigit < secondFromLeftDigit) return false;
            num = num/10;
        }
        // if number is now 0, it's consecutive:
        return true;
    }

    public static void main(String[] args) {
        try {
            java.util.Scanner keyboardReader = new java.util.Scanner(System.in);
            int number = keyboardReader.nextInt();

            System.out.println(
                            "Input number is " + 
                            (isConsecutive(number) ? "" : "not ") + 
                            "consecutive"
                    );
        } catch (Exception e) {
            System.out.println("Somthing is wrong with the input: ");
            e.printStackTrace();
        }
    }
}

    Upvotes: 0

    • Dhaval
    Dhaval

    Reputation: 1076

    I understand your concern. Unlike C language, java only accepts boolean with these operators.

    in C nonzero is true and zero is false

    (w=0) would return 0 which is integer. while (w==0) will return true/false which is boolean.

    although you might have made a logical error by writing w=0 instead of w==0, C compiler would not generate a compilation error as it gets a value. Whereas java needs boolean. Thus it will show an error.

    Upvotes: 0

    kdureidy
    kdureidy

    Reputation: 960

    You have two issues:

    1- As Amir said:

    isTwoDigitConsecutive = (w == 0) && (x == 0) && (y <== 9) && (y - z ==1);

    2- Small fix to w,x,y,z

    w = (number - (number % 1000)) / 1000;
x = ((number - (number % 100)) % 1000) / 100;
y = ((number - (number % 10)) % 100) / 10;
z = (number % 10);

    Also dont forget to initialize the variables isThreeDigitConsecutive and isFourDigitConsecutive

    Upvotes: 0

    Amir Kost
    Amir Kost

    Reputation: 2168

    Try isTwoDigitConsecutive = (w == 0) && (x == 0) && (y <== 9) && (y - z ==1); When you use the == sign, the compiler checks for equality. If you're using a single =, it assigns the right part of the = sign to the left part.

    Upvotes: 2

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