You can use while and until loops to iterate over arrays and other collections.
For example, the following code shows two ways of iterating over all the elements in an array:
arr= [1,2,3,4,5] i = 0 # ww w . j a v a 2s . c o m while i < arr.length puts(arr[i]) i += 1 end i=0 until i == arr.length puts(arr[i]) i +=1 end