Python While Loop

A while loop in Python is used to repeat a block of code as long as a condition is true. Use it when the number of iterations is not known in advance.

Python में while loop का उपयोग तब किया जाता है जब किसी condition के true रहने तक कोड को बार-बार चलाना हो। इसका उपयोग तब होता है जब loop कितनी बार चलेगा यह पहले से तय नहीं हो।

1. Print numbers from 1 to 5

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

   Output:

   1
   2
   3
   4
   5

2. Print even numbers up to 10

   i = 2
   while i <= 10:
       print(i)
       i += 2

   Output:

   2
   4
   6
   8
   10

3. Print countdown from 5 to 1

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

   Output:

   5
   4
   3
   2
   1

4. Sum of numbers from 1 to 10

   i = 1
   sum = 0
   while i <= 10:
       sum += i
       i += 1
   print("Sum:", sum)

   Output:

   Sum: 55

5. Print square of numbers 1 to 5

   i = 1
   while i <= 5:
       print(i*i)
       i += 1

   Output:

   1
   4
   9
   16
   25

6. Print table of 3

   i = 1
   while i <= 10:
       print("3 x", i, "=", 3*i)
       i += 1

   Output:

   3 x 1 = 3
   3 x 2 = 6
   ...
   3 x 10 = 30

7. Take input until user types 'exit'

   user_input = ""
   while user_input != "exit":
       user_input = input("Enter something (type 'exit' to stop): ")

   Output:

   Enter something (type 'exit' to stop): hello
   Enter something (type 'exit' to stop): world
   Enter something (type 'exit' to stop): exit

8. Reverse a number

   n = 1234
   rev = 0
   while n != 0:
       digit = n % 10
       rev = rev * 10 + digit
       n //= 10
   print("Reversed:", rev)

   Output:

   Reversed: 4321

9. Factorial of a number (e.g., 5)

   n = 5
   fact = 1
   while n > 0:
       fact *= n
       n -= 1
   print("Factorial:", fact)

   Output:

   Factorial: 120

10. Print characters of a string using while

    s = "Python"
    i = 0
    while i < len(s):
        print(s[i])
        i += 1

    Output:

    P
    y
    t
    h
    o
    n