The built-in function range() is used to return a sequence of integer numbers by specifying starting and ending points in the sequence. This resultant sequence is immutable means values cannot be changed. For repeating a task a specific number of times we can use this range() method with loops.
range(stop) range(start, stop[, step]) #where stop is an integer indicates stop position.
Takes three parameters. If the start index is not given it starts from 0, and it will increment the value by 1 continue until the stop index.
|Parameter||Description||Required / Optional|
|start||An integer number specifying at which position to start. Default is 0||optional|
|stop||An integer number specifying at which position to stop||Required|
|step||An integer determines the increment between each integer in the sequence||optional|
The result sequence is starting from 0 to stop - 1.if the stop is negative or 0 it returns an empty sequence.
r[n] = start + step*n (for both positive and negative step)
where, n >=0 and r[n] < stop (positive step)
where, n >= 0 and r[n] > stop (negative step)
If the step is zero it raises a ValueError exception. If non zero it returns a sequence according to the formula. If it doesn't meet the value constraint, an empty sequence is returned.
# empty range print(list(range(0))) # using range(stop) print(list(range(10))) # using range(start, stop) print(list(range(1, 10)))
 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [1, 2, 3, 4, 5, 6, 7, 8, 9]
start = 2 stop = 14 step = 2 print(list(range(start, stop, step)))
[2, 4, 6, 8, 10, 12]
start = 2 stop = -14 step = -2 print(list(range(start, stop, step))) # value constraint not met print(list(range(start, 14, step)))
[2, 0, -2, -4, -6, -8, -10, -12]