Loop backwards using indices

Try range(100,-1,-1), the 3rd argument being the increment to use (documented here).

("range" options, start, stop, step are documented here)

In my opinion, this is the most readable:

for i in reversed(xrange(101)):
    print i,

for i in range(100, -1, -1)

and some slightly longer (and slower) solution:

for i in reversed(range(101))

for i in range(101)[::-1]

You might want to use the reversed function in python. Before we jump in to the code we must remember that the range function always returns a list (or a tuple I don't know) so range(5) will return [0, 1, 2, 3, 4]. The reversed function reverses a list or a tuple so reversed(range(5)) will be [4, 3, 2, 1, 0] so your solution might be:

for i in reversed(range(100)):
    print(i)

I wanted to loop through a two lists backwards at the same time so I needed the negative index. This is my solution:

a= [1,3,4,5,2]
for i in range(-1, -len(a), -1):
    print(i, a[i])

Result:

-1 2
-2 5
-3 4
-4 3
-5 1

You can also create a custom reverse mechanism in python. Which can be use anywhere for looping an iterable backwards

class Reverse:
    """Iterator for looping over a sequence backwards"""
    def __init__(self, seq):
        self.seq = seq
        self.index = len(seq)

    def __iter__(self):
        return self

    def __next__(self):
        if self.index == 0:
            raise StopIteration
        self.index -= 1
        return self.seq[self.index]


>>> d = [1,2,3,4,5]
>>> for i in Reverse(d):
...   print(i)
... 
5
4
3
2
1

Oh okay read the question wrong, I guess it's about going backward in an array? if so, I have this:

array = ["ty", "rogers", "smith", "davis", "tony", "jack", "john", "jill", "harry", "tom", "jane", "hilary", "jackson", "andrew", "george", "rachel"]


counter = 0   

for loop in range(len(array)):
    if loop <= len(array):
        counter = -1
        reverseEngineering = loop + counter
        print(array[reverseEngineering])

It works well with me

for i in range(5)[::-1]:
    print(i,end=' ')

output : 4 3 2 1 0