Check to see if an array is already sorted?

Question

I know how to put an array in order, but in this case I just want to see if it is in order. An array of strings would be the easiest, I imagine, and answer

Answer 1

def ascending? (array)
    yes = true
    array.reduce { |l, r| break unless yes &= (l[0] <= r[0]); l }
    yes
end


def descending? (array)
    yes = true
    array.reduce { |l, r| break unless yes &= (l[0] >= r[0]); l }
    yes
end

Answer 2

If it turns out the array isn't sorted, will your next action always be to sort it? For that use case (though of course depending on the number of times the array will already be sorted), you may not want to check whether it is sorted, but instead simply choose to always sort the array. Sorting an already sorted array is pretty efficient with many algorithms and merely checking whether an array is already sorted is not much less work, making checking + sorting more work than simply always sorting.