# How to implement Reverse Loop in Python

Quick Answer

``````
for i in range(3,0,-1):
print('Reverse Python Loop-%d' %(i))
``````

Output

```Reverse Python Loop-3
Reverse Python Loop-2
Reverse Python Loop-1
```

Detail Explanation

In C/C++ programming we can do something like:

```for(i=5;i>0;i--)
{
printf("%d\t", i);
}
```

to loop backward (reverse) to produce output like:

```5    4    3    2    1
```

In python same thing can be achieved by using `range()` function with third arguments. To understand this, first we need to understand `range()` function in detail. Let's look at this first:

First, let's run:

``````
for i in range(5):
print(i)
``````

Which gives:

```0
1
2
3
4
```

In above program `range(5)` generates number 0, 1, 2, 3, 4 and we iterate through them to print. In general when one argument say (n) is given to range function then it generates number from 0 to n-1 and each time updating value by 1.

Second, let's run:

``````
for i in range(2,5):
print(i)
``````

Which gives:

```2
3
4
```

In above program `range(2,5)` generates number 2, 3, 4 and we iterate through them to print. In general when two arguments say (n1, n2) are given to range function then it generates number from n1 to n2-1 and each time updating value by 1.

Third, let's run:

``````
for i in range(1,8,2):
print(i)
``````

Which gives:

```1
3
5
7
```

In above program `range(1,8,2)` generates number 1, 3, 5, 7 and we iterate through them to print. In general when three arguments say (n1, n2, n3) are given to range function then it generates number from n1 to n2-1 with update value of n3.

So, to implement reverse loop we can use negative value in update argument of range function.

## Python Reverse Loop Example

``````
for i in range(8,0,-1):
print('Reverse Python Loop-%d' %(i))
``````

Output of above program is:

```Reverse Python Loop-8
Reverse Python Loop-7
Reverse Python Loop-6
Reverse Python Loop-5
Reverse Python Loop-4
Reverse Python Loop-3
Reverse Python Loop-2
Reverse Python Loop-1
```