Loops in Python

 Loops in Python

Loops in Python are used to repeat actions efficiently.

Types of Loops

The main types are For loops (counting through items) and While loops (based on conditions).

While Loop

while loop is used to execute a block of statements repeatedly until a given condition is satisfied. When the condition becomes false, the line immediately after the loop in the program is executed.

Ex.

count = 1

while count <= 3:

    count = count + 1

    print("Hello World")

Output

Hello World

Hello World

Hello World

Example

 

1) Generate Counting 1 to 10. 

num = 1

while num<= 10:

    print(num)

    num = num + 1

else:

    print("loop finished")

Output

1

2

3

4

5

6

7

8

9

10

loop finished

2) Create table using with Input Method

val = int(input("Enter a Number to Create a table:"))

no=1

while no<= 10:

    print(no*val)

    num = num + 1

else:

    print("loop finished")

  

Output

Enter a Number to Create a table: 5

5

10

15

20

25

30

35

40

45

50

loop finished

3) Create Program Print Natural Number

a=int(input("Enter any no :"))

no = 1

while no<= 10:

    print(no)

    no = no + 1

else:

    print("loop finished")

Output

Enter any no : 10

1

2

3

4

5

6

7

8

9

10

loop finished

4) Create Reverse Counting (10 to 1)  Printing Program.

a=int(input("Enter any no :"))

no = 10

while no>= 1:

    print(no)

    no = no - 1

else:

    print("loop finished")

Output

Enter any no : 10

10

9

8

7

6

5

4

3

2

1

loop finished

5) The continue Statement

With the continue statement we can stop the current iteration, and continue with the next:

i = 0

while i < 6:

  i += 1

  if i == 3:

    continue

  print(i)

# Note that number 3 is missing in the result

Output

1

2

4

5

6

6) The else Statement

With the else statement we can run a block of code once when the condition no longer is true:

i = 1

while i < 6:

  print(i)

  i += 1

else:

  print("i is no longer less than 6")

Output

1

2

3

4

5

i is no longer less than 6

7) Continue Statement Multiple Conditions 

i = 0

while i < 10:

    if i == 3:

        i += 1  

        continue

    elif i == 6:

        i += 1  

        continue

    elif i == 8:

        i += 1  

        continue

    print(i)

    i += 1

Output

0

1

2

4

5

7

9

8) Break Statement

i = 1

while i < 6:

  print(i)

  if (i == 3):

    break

  i += 1

Output

1

2

3

 For Loops

Python for loops are used for iterating over sequences like lists, tuples, strings and ranges.

A for loop allows you to apply the same operation to every item within the loop.

Using a for loop avoids the need to manually manage the index.

A for loop can iterate over any iterable object, such as a dictionary, list or custom iterator.

Ex. 

s = ["One", "Two", "Three"]

for i in s:

    print(i)

Output

One

Two

Three

1) Iterating over characters of strings

This code uses a for loop to iterate over a string and print each character on a new line.

s = "AD COMPUTER CAMPUS"

for i in s:

    print(i)

Output

A

D

C

O

M

P

U

T

E

R

C

A

M

P

U

S

Using range() with For Loop

2) Printing Number with One (Stop) Argument

for i in range(7)

     print(i)

Output

0

1

2

3

4

5

6

3) Printing Number with Two (Start, Stop) Argument

for i in range(7,13)

     print(i)

Output

7

8

9

10

11

12

3) Printing Number with Three (Start, Stop,Step) Argument

for i in range(10,50,3)

     print(i)

Output

10

15

20

25

30

35

40

45