Python Basics — Day 7 While Loops + Mini Projects

01. Basic Structure of a while Loop

• Repeats as long as the condition is True

• Stops when the condition becomes False

count = 1
while count <= 5:
    print("Hello", count)
    count += 1

👉 Output:

Hello 1
Hello 2
Hello 3
Hello 4
Hello 5

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02. Infinite Loops with while

If the condition is always True, the loop runs forever.
Usually, break is used to exit.

while True:
    cmd = input("Enter q to quit: ")
    if cmd == "q":
        print("Program terminated!")
        break

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03. Using continue

Skip the current iteration and move to the next one.

num = 0
while num < 10:
    num += 1
    if num % 2 == 0:
        continue
    print(num)   # Prints only odd numbers

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04. While vs For

• for loop → when the number of repetitions is fixed

• while loop → when repetitions depend on a condition and may vary

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05. Practice Examples

Example 1: Print Numbers 1 to 10

n = 1
while n <= 10:
    print(n)
    n += 1

Example 2: Password Checker

password = "1234"

while True:
    guess = input("Enter password: ")
    if guess == password:
        print("Login successful!")
        break
    else:
        print("Incorrect. Try again.")

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06. Mini Projects ✨

(1) Multiplication Table

dan = int(input("Enter a number for the times table: "))
i = 1

while i <= 9:
    print(f"{dan} x {i} = {dan * i}")
    i += 1

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(2) Sum Calculator

Keeps adding numbers entered by the user until 0 is typed.

total = 0

while True:
    num = int(input("Enter a number (0 to quit): "))
    if num == 0:
        break
    total += num

print("Total sum:", total)

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(3) Number Guessing Game

import random

secret = random.randint(1, 20)  # Random number between 1 and 20
tries = 0

while True:
    guess = int(input("Guess the number (1–20): "))
    tries += 1
    if guess == secret:
        print(f"Correct! You guessed it in {tries} tries.")
        break
    elif guess < secret:
        print("Try a higher number.")
    else:
        print("Try a lower number.")