Integer variable stores 0 as method return value

user_13573336 0
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I was trying Binary Search recursive program in Java, the algorithm seems to be perfectly fine, but the variable in which I store the result from the recursive function, is storing 0 as the value. In the following code, I want to store the index of the element found in the variable result, but the output prints result's value as 0. When I print the value of mid before the return statement, the value is correct. How to fix this problem??

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        int n;
        System.out.println("Enter the number of elements in the array: ");
        n = scanner.nextInt();

        int arr[] = new int[n];
        System.out.println("Enter the array elements (from index 0): ");
        for (int i = 0; i < n; i++) {
            arr[i] = scanner.nextInt();
        }

        int ele;
        System.out.println("Enter the element to be searched: ");
        ele = scanner.nextInt();
/*************************************************************************************/
        int result = binarySearchRecursive(arr, 0, n - 1, ele);
        System.out.println(result);
/************************************************************************************/

        if (result == -1) {
            System.out.println(ele + " not found");
        } else {
            System.out.println(ele + " found at index: " + result);
        }


    }

    //Algorithm

    public static int binarySearchRecursive(int arr[], int l, int r, int ele) {

        //Check whether a single element is present
        if (l == r) {
            if (arr[l] == ele) {
                return l;
            } else {
                return -1;
            }
        } else {      //Multiple elements
            int mid = (l + r) / 2;

            //Check conditions
            if (ele == arr[mid]) {
                System.out.println("Method return 'mid' value: "+mid);
                return mid;
            } else if (ele < arr[mid]) {
                binarySearchRecursive(arr, l, mid - 1, ele);
            } else {
                binarySearchRecursive(arr, mid + 1, r, ele);
            }

        }

        return -l;
    }

}

Here is the output

recursion binary search variables java
2 Answers

You should return the value of the recursive calls:

        if (ele == arr[mid]) {
            System.out.println("Method return 'mid' value: "+mid);
            return mid;
        } else if (ele < arr[mid]) {
            return binarySearchRecursive(arr, l, mid - 1, ele);
        } else {
            return binarySearchRecursive(arr, mid + 1, r, ele);
        }
user_12215710

You have to add return statements to the recursive function calls of binarySearchRecursive. Right now your code is always falling through to the last return statement which just returns -l => which returns 0 for binarySearchRecursive(arr, 0, n - 1, ele);

    return binarySearchRecursive(arr, l, mid - 1, ele);

    return binarySearchRecursive(arr, mid + 1, r, ele);
user_141576770
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