For Loop in Python

A loop is a used for iterating over a set of statements again and again. There are three types of loops for, while and do-while in python.

Syntax:

for <variable> in <sequence>:

Here <variable> is a variable that is used for iterating over a <sequence>. All iteration it takes the next value from <sequence> until the last of series is reached.

Example:

Program to print squares of all numbers present in a list

num = [1, 2, 3, 4, 5]

sq = 0

for i in num:

sq = i*i

print(sq)

Output:

1

4

9

16

25

Python for loop example using range () function

Program to print the sum of first 3 natural numbers

sum = 0

for i in range(1, 4):

sum = sum + i

print(sum)

Output:

6

For loop with else block

for i in range(5):

print(i)

else:

print("The loop has completed execution")

Output:

0

1

2

3

4

The loop has completed execution

Nested For loop in Python

When a for loop is present inside another for loop then it is called a nested for loop.

for i in range(3):

for j in range(9, 13):

print(i, ",", j)

Output:

0 , 9

0 , 10

0 , 11

0 , 12

1 , 9

1 , 10

1 , 11

1 , 12

2 , 9

2 , 10

2 , 11

2 , 12