Kailash - 1 year ago 172

Java Question

As per Java doc for Arrays.binarySearch(int[] a, int key)

Returns:

index of the search key, if it is contained in the array;

otherwise, (-(insertion point) - 1). The insertion point is defined as

the point at which the key would be inserted into the array: the index

of the first element greater than the key, or a.length if all elements

in the array are less than the specified key. Note that this

guarantees that the return value will be >= 0 if and only if the key

is found.

I need to understand why its returning

`(-(insertion point) - 1)`

`-(insertion point)`

Answer Source

Because if it returned `-(insertion point)`

, and the insertion point was 0, then you would not be able to distinguish between *I found it, it's at index 0*, and *I haven't found it, you can insert at index 0*.