Iterative Constructs in Java

Chapter 9

Iterative Constructs in Java

Class 10 - Logix Kips ICSE Computer Applications with BlueJ

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Java Program: Menu-Driven Program: Fibonacci or Sum of Digits

25. Using the switch statement, write a menu driven program to:

(1). Generate and display the first 10 terms of the Fibonacci series 0, 1, 1, 2, 3, 5....

The first two Fibonacci numbers are 0 and 1, and each subsequent number is the sum of the previous two.

(2). Find the sum of the digits of an integer that is input.
Sample Input: 15390
Sample Output: Sum of the digits = 18

For an incorrect choice, an appropriate error message should be displayed.

Program Title: Menu-Driven Program: Fibonacci or Sum of Digits

Java

import java.util.Scanner;
 
public class MenuDrivenProgram {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
 
        System.out.println("MENU");
        System.out.println("1. First 10 terms of Fibonacci series");
        System.out.println("2. Sum of digits of a number");
        System.out.print("Enter your choice: ");
        int choice = sc.nextInt();
 
        switch (choice) {
            case 1:
                // Fibonacci series
                int n = 10; // first 10 terms
                int a = 0, b = 1;
                System.out.print("Fibonacci Series: " + a + " " + b + " ");
                for (int i = 3; i <= n; i++) {
                    int c = a + b;
                    System.out.print(c + " ");
                    a = b;
                    b = c;
                }
                System.out.println();
                break;
 
            case 2:
                // Sum of digits
                System.out.print("Enter a number: ");
                int num = sc.nextInt();
                int temp = num;
                int sum = 0;
 
                while (temp != 0) {
                    sum += temp % 10;
                    temp /= 10;
                }
 
                System.out.println("Sum of the digits = " + sum);
                break;
 
            default:
                System.out.println("Invalid choice! Please select 1 or 2.");
        }
 
        sc.close();
    }
}

Output

Sample Output 1 (Fibonacci)
MENU
1. First 10 terms of Fibonacci series
2. Sum of digits of a number
Enter your choice: 1
Fibonacci Series: 0 1 1 2 3 5 8 13 21 34

Sample Output 2 (Sum of Digits)
MENU
1. First 10 terms of Fibonacci series
2. Sum of digits of a number
Enter your choice: 2
Enter a number: 15390
Sum of the digits = 18

📝 Explanation

Option 1 (Fibonacci):

Starts with 0 and 1, calculates each term as sum of previous two.

Option 2 (Sum of digits):

Extract digits using % 10 and sum them in a loop.

Default: Handles invalid menu input.