Python while

 

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Python's while loop lets you repeat a block of code as long as a certain condition is true. Think of it like a repeating instruction that only stops when you tell it to.

Basic Structure:

while condition:
    # code to run

Example 1: Basic Countdown

count = 5
while count > 0:
    print(count)
    count -= 1

Explanation: The loop prints numbers from 5 to 1. It stops when count is no longer greater than 0.

Example 2: Simple User Prompt

password = ""
while password != "1234":
    password = input("Enter your password: ")

Explanation: The loop keeps asking for a password until the user enters "1234".

Example 3: Adding Numbers Until Zero

total = 0
number = int(input("Enter a number: "))
while number != 0:
    total += number
    number = int(input("Enter another number (0 to stop): "))
print("Total:", total)

Explanation: The loop adds up numbers entered by the user until they enter 0.

Example 4: Looping Through a List

fruits = ["apple", "banana", "cherry"]
i = 0
while i < len(fruits):
    print(fruits[i])
    i += 1

Explanation: The loop prints each fruit in the list by checking each index.

Example 5: Simple Guessing Game

secret_number = 7
guess = int(input("Guess the number: "))
while guess != secret_number:
    guess = int(input("Wrong! Try again: "))
print("Correct!")

Explanation: The loop continues until the user guesses the correct number.

Example 6: Even Number Printer

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

Explanation: The loop prints even numbers from 2 to 10.

Example 7: Infinite Loop (Be Careful!)

while True:
    print("This will go on forever unless you stop it!")

Explanation: This loop never stops because the condition is always true.

Example 8: Exit Loop with break

count = 1
while count <= 5:
    print(count)
    if count == 3:
        break
    count += 1

Explanation: The loop stops when count reaches 3 because of the break statement.

Example 9: Skipping with continue

count = 0
while count < 5:
    count += 1
    if count == 3:
        continue
    print(count)

Explanation: The loop skips printing the number 3 because of the continue statement.

Example 10: Factorial Calculation

number = 5
result = 1
while number > 0:
    result *= number
    number -= 1
print("Factorial:", result)

Explanation: The loop calculates the factorial of 5 (5 * 4 * 3 * 2 * 1).

Each of these examples uses a while loop to repeat tasks until certain conditions are met, helping you perform tasks in a more efficient and controlled way.