Variable declaration in BinarySearch

Question

I am working on a java project BinarySearch. I'm trying to create and initialize a variable mid which will find out the middle value but it is giving me an error that you can't declare a variable here. I also tried it with the split declaration but it didn't work. Here is my piece of code:

 public static boolean binarySearch(int[] data, int target, int low, int high){
        if(low>high)
            return false;
        else
            int mid=(low + high )/2;
        if(target==data[mid]);
            return true;
        else if(target<data[mid])
            return binarySearch(data, target, low, mid - 1);
        else
            return binarySearch(data, target, mid + 1, high);


    }

What should I do to solve this problem?

Answer 1

You have done two mistakes here.

• First you have to declare mid variable in the beginning, since it using in other scopes too (Not only in else scope).
• Second one is you have to remove the semicolon here if(target==data[mid]);. Since it's terminating the line.

Code after fixing those issues,

public static boolean binarySearch(int[] data, int target, int low, int high){
  int mid;
  if (low > high)
    return false;
  else
    mid = (low + high) / 2;
  if (target == data[mid])
    return true;
  else if (target < data[mid])
    return binarySearch(data, target, low, mid - 1);
  else
    return binarySearch(data, target, mid + 1, high);
}