for Loop

The for loop iterate over a sequence.

What is a for loop?

The for loop in Python is used to iterate over a sequence (listtuplestring) or other iterable objects. Iterating over a sequence is called traversal.

​​​​​​​Syntax

for value in sequence:

    statement(s)

How for loop works?

The variable value holds the element of the sequence on each iteration.

Loop terminates once the last item is iterated in the sequence.

The   ‘for’ block starts with the first intended code line and ends with the first unindented line of code.

Example:

for char in 'Python'

          print(char)

​​​​​​​The below table demonstrates how each iteration works in the above code example

Iteration number

End of  sequence

Value of  variable char

1

No

'P'

2

No

'y'

3

No

't'

4

No

'h'

5

No

'o'

6

No

'n'

7

Yes

Exit Loop

 

Flowchart of for Loop

For Loop in Python

 

Flowchart of for Loop in Python

​​​​​​​Example: 1

# print welcome to all the names in the list

# List of the names

names = ['Ashish', 'Narayan', 'Mahesh', 'Ramesh']

# iterate over the list

for name in names:

            print("Welcome " , name)

Output

Welcome  Ashish

Welcome  Narayan

Welcome  Mahesh

Welcome  Ramesh

Example: 2

vowels = ('a', 'e', 'i', 'o','u' )

# iterate over the list

for vowel in vowels:

          print("Vowel " , vowel)

Output

Vowel  a

Vowel  e

Vowel  i

Vowel  o

Vowel  u

Example: 3

# iterate over the range

for val in range(1,11):

          print("value is " , val)

Output

value is  1

value is  2

value is  3

value is  4

value is  5

value is  6

value is  7

value is  8

value is  9

value is  10

 

for loop with else

The 'for' loop can have an optional ‘Else’ block. The Else part is executed if the for loop is exhausted

Example: 4

#len function returns the number of elements in the list

for element in range(len(primeno_list)):

             print(element)

else:

    print("Finished printing list")

Output

0

1

2

3

4

5

6

7

8

9

Finished printing list

Note:

Here, the for loop prints element of the list one by one until the loop exhausts. After  for loop exhausts, it executes the else block and prints the Finished printing list

In case a break statement is encountered in the 'for' loop, the else part is ignored.