Python While Loop

A while loop runs as long as the condition is True.

# infinite loop
while True:
    print("hello world")

Note

Do not create infinite loops unless needed — they will run forever (unstoppable).

Info

In real life, infinite loops are used in systems like servers, games, etc.

Question

Write a program in Python to print “hello world” five times

count = 1 # iterator
 
while count <= 5:
    print("hello world")
    count += 1

output

hello world
hello world
hello world
hello world
hello world

Dry Run Table

count	condition (count ⇐ 5)	output
1	True	hello world
2	True	hello world
3	True	hello world
4	True	hello world
5	True	hello world
6	False	stop
The loop stops when the condition becomes `False`.

Question

Write a program in Python to print numbers from 1 to 5

count = 1
 
while count <= 5:
    print(count)
    count += 1

output

Question

Write a program in Python to print numbers from 5 to 1

count = 5
 
while count >= 1:
    print(count)
    count -= 1

output

Important

Most loops start from 0 (especially in programming)

Example: range(0, n)

But you can start from any number depending on your need

Question

Write a program in Python to print the multiplication table of any number n

n = int(input("enter a number: "))
i = 1
 
while i <= 10:
    print(n, "x", i, "=", n * i)
    i += 1

output

enter a number: 5
5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50

Second Brain