function binarySearch(array, searchItem) do
    start = 0
    emd = array.length-1
    mid

    while (start <= end) do
        mid = (start + emd) / 2
        if (array[mid] > searchItem) do
            emd = mid - 1
        end else if (array[mid] < searchItem) do
            start = mid + 1
        end else do
            return "search item found at index " + mid
        end
    end
end