LOOPS IN PYTHON

Share via:

Post Views: 223

Python language provides three types of loops, They are :

while loop
for loop
nested loop

Loop : It is a sequence of statements that will be repeated continuously until a certain condition is met.

While Loop : It is used to execute a block of statements repeatedly till a given condition is True. It will check the condition before executing the loop.

Syntax :

while(Condition):
statements

1 2	while(Condition): statements

Example :

1 counter = 1
2 while counter <= 5:
3 print(counter)
4 counter += 1

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

1 counter = 1

2 while counter <= 5:

3 print(counter)

4 counter += 1

Output

-------------

For Loop : for loop in python is different from the for in other programming languages. In Python a for loop is used to iterate over a set of items, list of items or any sequence of items.

Example 1 :

1 Students = ["Lucy", "Ryan", "Chris"]
2 for i in Students:
3 print(i)

Output
------------
Lucy
Ryan
Chris

1 Students = ["Lucy", "Ryan", "Chris"]

2 for i in Students:

3 print(i)

Output

------------

Lucy

Ryan

Chris

Example 2 :

for i in range(5):
print(i, end=" ")

Output
--------------
0 1 2 3 4

for i in range(5):

print(i, end=" ")

Output

--------------

0 1 2 3 4

You might wonder what is the word range in the above example. Let me explain it.

Range function : Range function iterates over a piece of code a speciﬁc number of times.

It auto increments the number until the speciﬁc number of iterations are reached.

range( 5 ) denotes the values from 0 to 4 excluding
range( 2, 5 ) denotes the values starting from 2 to 4 excluding
range( 3, 20, 2 ) denotes the values starting from 3 to 20 incrementing the sequence by 2 each

Example 1 :

for i in range(5):
print(i, end=" ")

Output
------------------
0 1 2 3 4

for i in range(5):

print(i, end=" ")

Output

------------------

0 1 2 3 4

Example 2 :

for i in range(2,5):
print(i, end=" ")

Output
-----------------
2 3 4

for i in range(2,5):

print(i, end=" ")

Output

-----------------

2 3 4

Example 3 :

for i in range (2,20, 2):
print(i,end=" ")

Output
----------------------
2 4 6 8 10 12 14 16 18

for i in range (2,20, 2):

print(i,end=" ")

Output

----------------------

2 4 6 8 10 12 14 16 18

Break Statement : Break Statement is used to terminate or stop the ﬂow of execution of code before it reaches the stopping condition or before iteration of all the items are completed.

Example 1 :

for i in range(7):
if i == 4:
break
print(i, end=" ")

Output
--------------------
0 1 2 3

for i in range(7):

if i == 4:

break

print(i, end=" ")

Output

--------------------

0 1 2 3

Example 2 :

1 counter = 1
2 while counter <= 6:
3   if counter == 4:
4      break
5   print(counter, end = " ")
6   counter += 1

Output 
--------------------
1 2 3

1 counter = 1

2 while counter <= 6:

3 if counter == 4:

4 break

5 print(counter, end = " ")

6 counter += 1

Output

--------------------

1 2 3

Continue Statement : Continue Statement is used to stop the current iteration continuing from the next

Example 1 :

1 for i in range(7):
2   if i == 4:
3     continue
4   print(i, end=" ")

Output 
--------------------
0 1 2 3 5 6

1 for i in range(7):

2 if i == 4:

3 continue

4 print(i, end=" ")

Output

--------------------

0 1 2 3 5 6

Example 2 :

1 counter = 1
2   while counter <= 6:
3   if counter == 4:
4      continue
5   print(counter, end = " ")
6   counter += 1

Output
---------------------
1 2 3