If we want to execute a group of statements multiple times then we should go for Iterative statements.
Python supports 2 types of iterative statements;
- for loop
- while loop

For Loop

If we want to execute some action for every element present in some sequence(it may be string or collection) then we should go for for loop.

Syntax

Python

for x in sequence:
  body

sequence can be string or any collection.
Body will be executed for every element present in the sequence.

Question

To print characters present in the given string

Python

s="Ajay Shukla" 
for x in s:
  print(x)

Output

PowerShell

A
j
a
y
 
S
h
u
k
l
a

Question

To print characters present in string index wise:

Python

s=input("Enter some String: ")
i=0
for x in s:
  print("The character present at ",i,"index is :",x)
i=i+1

Output

PowerShell

Enter some String: Ajay Shukla
The character present at  0 index is : A
The character present at  0 index is : j
The character present at  0 index is : a
The character present at  0 index is : y
The character present at  0 index is :  
The character present at  0 index is : S
The character present at  0 index is : h
The character present at  0 index is : u
The character present at  0 index is : k
The character present at  0 index is : l
The character present at  0 index is : a

Question

To print Hello 10 times

Python

for x in range(10):
  print("Hello")

Output

PowerShell

Hello
Hello
Hello
Hello
Hello
Hello
Hello
Hello
Hello
Hello

Question

To display numbers from 0 to 10.

Python

for x in range(11):
  print(x)

Output

PowerShell

Question

To display odd numbers from 0 to 20.

Python

for x in range(21):
  if(x%2!=0):
    print(x)

Output

PowerShell

Question

To display numbers from 10 to 1 in descending order.

Python

for x in range(10,0,-1):
  print(x)

Output

PowerShell

Question

To print sum of numbers presents inside list.

Python

list=eval(input("Enter List:"))
sum=0
for x in list:
  sum=sum+x; 
print("The Sum = ",sum)

Output

PowerShell

Enter List:[1,2,3,4,5]
The Sum = 15

PowerShell

Enter List:[50,780]
The Sum = 830

While Loop

If we want to execute a group of statements iteratively until some condition false, then we should go for while loop.

Syntax

Python

while condition:
  body

Question

To print numbers from 1 to 10 by using while loop.

Python

x=1 
while x <=10:
  print(x)
  x=x+1

Output

PowerShell

Question

To display the sum of first n numbers.

Python

n=int(input("Enter number:"))
sum=0
i=1
while i<=n:
  sum=sum+i
  i=i+1
print("The sum of first",n,"numbers is :",sum)

Output

PowerShell

Enter number:20
The sum of first 20 numbers is : 210

Question

Write a program to prompt user to enter some name until entering ajay.

Python

name=""
while name!="ajay":
  name=input("Enter Name:")
print("Thanks for confirmation")

Output

PowerShell

Enter Name:ajay
Thanks for confirmation

Infinite Loops

Python

i=0
while True:
  i=i+1
  print("Hello",i)

Output

PowerShell

Hello 1
Hello 2
Hello 3
...
...

Nested Loops

Sometimes we can take a loop inside another loop, Which are also known as nested loops.

Example

Python

for i in range(4):
  for j in range(4):
    print("i=",i," j=",j)

Output

PowerShell

i= 0  j= 0
i= 0  j= 1
i= 0  j= 2
i= 0  j= 3
i= 1  j= 0
i= 1  j= 1
i= 1  j= 2
i= 1  j= 3
i= 2  j= 0
i= 2  j= 1
i= 2  j= 2
i= 2  j= 3
i= 3  j= 0
i= 3  j= 1
i= 3  j= 2
i= 3  j= 3

Question

Write a program to display *’s in Right angled triangled form

Python

n = int(input("Enter number of rows:"))
for i in range(1,n+1):
  for j in range(1,i+1):
    print("*",end=" ")
  print()

Output

PowerShell

Enter number of rows:10
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
* * * * * * * * * *

Python

n = int(input("Enter number of rows:"))
for i in range(1,n+1):
  print("*"*i)

Output

PowerShell

Enter number of rows:10
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
* * * * * * * * * *

Question

Write a program to display *’s in pyramid.

Python

n = int(input("Enter number of rows:"))
for i in range(1,n+1):
  print(" " * (n-i),end="")
  print("* "*i)

Output

PowerShell

Enter number of rows:10
         *
        * *
       * * *
      * * * *
     * * * * *
    * * * * * *
   * * * * * * *
  * * * * * * * *
 * * * * * * * * *
* * * * * * * * * *

Ungraded Questions

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