Looping statements
A loop statement allows us to execute a statement
or group of statements multiple times.
Looping statements
Types of Looping statements
For loop
While
loop
Nested
loop
For Loop
The for loop in python is
used to iterate the
statements or part of
the program several
times. It is frequently
used to traverse the
data structures like list,
tuple, or dictionary.
Flowchart
for iterating_var in sequence:
statements
Syntax
Write a
program to
print 1 to 10
series
i=1
For i in range(0,11):
Print(i)
Output
0 1 2 3 4 5 6 7 8 9
Example
To print
multiplication table
i=0
n=int(input("enter no"))
for i in range(0,11):
print("%d X %d = %d" %
(n,i,n*i))
enter no 6
6 X 0 = 0
6 X 1 = 6
6 X 2 = 12
6 X 3 = 18
6 X 4 = 24
6 X 5 = 30
6 X 6 = 36
6 X 7 = 42
6 X 8 = 48
6 X 9 = 54
6 X 10 = 60
Output
Program
to
Iterating
string
using for
loop
str = "Python"
for i in str:
print(i)
P
Y
T
H
O
N
Output
Example
Program to iterate through a
list using indexing
city = ['Bhopal', 'Indore', 'Gwalior',
'Ujjain', 'Sagar‘]
# iterate over the list using index
for i in range(len(city)):
print("I go to", city[i])
I go to Bhopal
I go to Indore
I go to Gwalior
I go to Ujjain
I go to Sagar
Output Example
While loop syntax
while (
test_expression):
Body of while
Repeats a statement or
group of statements while
a given condition is TRUE. It
tests the condition before
executing the loop body.
Flow chart
i = 1
while i < 6:
print(i)
i += 1
1
2
3
4
5
Output
Example
Program to
print 1 to 5
series
a =[‘student1', ‘student2',
‘student3']
while a:
(a.pop(-1))
Student3
Student2
Student1
Program to print list in reverse order
Example Output
10
9
8
7
6
5
4
3
2
1
Example
Output
n=10
while n > 0:
n -= 1;
if True: print(n)
Using if Statement with While Loop
Using else Statement with While Loop
Python supports to have
an else statement associated with a
loop statement.
If the else statement is used with
a while loop, the else statement is
executed when the condition becomes
false.
Syntax
while expr:
statement(s)
else:
additional_statement(s)
count = 0
while count < 5:
print count, " is
less than 5"
count = count + 1
else:
print count, " is
not less than 5"
0 is less than 5
1 is less than 5
2 is less than 5
3 is less than 5
4 is less than 5
5 is not less than 5
Program to print
series with else state
Example
Output
Find Even odd no
number = 2
while number < 10 :
# Find the mod of 2
if number%2 == 0:
print("The number
"+str(number)+" is even")
else:
print("The number
"+str(number)+" is odd")
# Increment `number` by 1
number = number+1
The number 2 is even
The number 3 is odd
The number 4 is even
The number 5 is odd
The number 6 is even
The number 7 is odd
The number 8 is even
The number 9 is odd
Output
Nested loop
2
3
5
7
11
13
prime no
i = 2
print("prime no")
while(i < 15):
j = 2
while(j <= (i/j)):
if not(i%j): break
j = j + 1
if (j > i/j) : print(i)
i = i + 1
You can use one or more
loop inside any another
while, for or do..while
loop.
Example
Program to
print given
pattern
5 4 3 2 1
5 4 3 2
5 4 3
5 4
5
while(i<=5):
j=5
while(j>=i):
print(j, end=' ‘)
j-=1
i+=1
print()
Output
Example
program to
print given
below
pattern
*
**
***
****
*****
rows = int(input("Enter the rows:"))
# Outer loop will print number of ro
ws
for i in range(0,rows+1):
# Inner loop will print number of Ast
risk
for j in range(i):
print("*",end = '')
print()
Example
Program to print
given pattern
1
22
333
4444
55555
rows = int(input("Enter the
rows"))
for i in range(0,rows+1):
for j in range(i):
print(i,end = '')
print()
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Looping statement in python