‘range()’
function is used to iterate over a sequence of numbers.
There are
two variants of range function.
class range(stop)
class range(start, stop[, step])
All the
arguments to range function are integers. By default start is assigned to 0,
step is assigned to 1. ‘range(5) is same as ‘range(0, 5).
test.py
for i in range(5): print(i)
$ python3
test.py
0
1
2
3
4
test.py
for i in range(0, 15, 3): print(i)
$ python3
test.py
0
3
6
9
12
If you assign
0 to the argument ‘step’ then ValueError thrown.
test.py
for i in range(0, 15, 0): print(i)
$ python3
test.py
Traceback
(most recent call last):
File "test.py", line 1, in
<module>
for i in range(0, 15, 0):
ValueError:
range() arg 3 must not be zero
test.py
for i in range(0, -10, -2): print(i)
$ python3
test.py
0
-2
-4
-6
-8
Check for a value in given range
By using
‘in’ operator you can check, whether given value is in range or not.
>>> 2 in range(0, 10, 2) True >>> 4 in range(0, 10, 2) True >>> 14 in range(0, 10, 2) False >>> 1 in range(0, 10, 2) False
By using
range(), len() functions, you can iterate over a sequence.
test.py
names=["Phalgun", "Sambith", "Mahesh", "swapna"] for i in range(len(names)): print(i, names[i]) else: print("Exiting from loop") print("Execution finished")
$ python3
test.py
0 Phalgun
1 Sambith
2 Mahesh
3 swapna
Exiting from
loop
Execution
finished
Note:
For a
positive step, the contents of a range r are determined by the formula r[i] =
start + step*i where i >= 0 and r[i] < stop.
For a
negative step, the contents of the range are still determined by the formula
r[i] = start + step*i, but the constraints are i >= 0 and r[i] > stop.
No comments:
Post a Comment