CODEWITHSUNDEEP
javaarraysreversing
Tripti Verma
Tripti Verma

Reputation: 13

prog.java:52: error: incompatible types: int cannot be converted to boolean for(int i=0;i=n/2;i++){

Does values in for loop gives boolean results in Java? Getting this error when I compiled the code:

prog.java:52: error: incompatible types: int cannot be converted to boolean for(int i=0;i=n/2;i++){

public static void reverseArray(int arr[], int n) {
    // Your code here
    
        int temp;
        int i=0;
        for(i=0;i=n/2;i++){
            temp = arr[i];
            arr[i]=arr[n-i];
            arr[n-i]=temp;
        }

    }

Upvotes: -1

Views: 2978

Answers (1)

Nowhere Man
Nowhere Man

Reputation: 19575

  1. The second parameter of for loop needs to be fixed to provide boolean expression: i < n/2
  2. When swapping elements, the index of the last element is n - i - 1 as the array indexes in Java are zero-based: [0..n - 1] make n elements.

Thus, the updated function may loo like this (with all relevant variable declarations moved inside for loop):

public static void reverseArray(int[] arr, int n) {
    for (int i = 0, j = n - 1; i < n/2; i++, j--) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
}

Also, the implemented method allows to reverse a part of n elements of the input array, so it may be better to have an overloaded version accepting only arr argument, and use minimal value of n and arr.length to prevent ArrayIndexOutOfBoundsException:

public static void reverseArray(int[] arr) {
    reverseArray(arr, arr.length);
}

public static void reverseArray(int[] arr, int n) {
    for (int i = 0, m = Math.min(n, arr.length), j = m - 1; i < m/2; i++, j--) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
}

Test:

int[] arr = {1, 2, 3, 4, 5};
      
reverseArray(arr, 3);

System.out.println("After reverse: " + Arrays.toString(arr));

Output:

After reverse: [3, 2, 1, 4, 5]

Upvotes: 1

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