`range()` is a special function that generates range of numbers. `range()` has three parameters:

`range(start, end, step)` - returns the numbers starting from `start` up to `end` (exclusive) with the step `step`.

### Examples



`range(1, 10, 1)`: returns (1, 2, 3, 4, 5, 6, 7, 8, 9).

`range(-3, 4, 3)`: returns (-3, 0, 3).

`range(22, 22, 1)`: returns empty range.

You can also use such a `range()` functions:

 - `range(end)`: the shorter version of `range(0, end, 1)`
 - `range(start, end)`: the shorter version of `range(start, end, 1)`.

Run the following examples to see the loop iteration.

for i in range(8):
  print(i)

for i in range(7, -1, -1):
  print(i)

for i in range(1, 11, 2):
  print(i)

Using `range()` in `for` loop condition helps to specify the `start` and `end` conditions, however set a `step`. By the way, variable that stores the value (here is an `i`) shouldn't be defined before the loop. It exists only inside the loop.

## Negative step

What happens if pass negative value of step? Actually, still the same: generates range of numbers starting with `start` decreasing down to `end` (still exclusive). The code to generate odd numbers between 8 and 20 in descending order:

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range()

Examples

Negative step

解答