🔁 Python While Loop — Repeat Actions Until a Condition Changes

Introduction 🌟

A while loop repeatedly executes a block of code as long as its condition remains True. It is ideal for situations where you don't know in advance how many times the loop should run.

Note

💡 Use a while loop when the number of iterations depends on a condition, not a fixed count.

1. Basic While Loop Structure 🧱

basic_while.py

i = 1

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

✔️ The loop starts at i = 1
✔️ Runs until i <= 5 becomes False
✔️ Each iteration increases i by 1

2. Infinite Loop ⚠️

A while loop becomes infinite if its condition never becomes False.

infinite_loop.py

while True:
    print("This will run forever!")

Note

⚠️ Avoid infinite loops unless intentionally used (like servers, listeners, etc.).

3. Using While Loop With User Input ⌨️

while_input.py

password = ""

while password != "admin":
    password = input("Enter password: ")

print("Access granted!")

4. While Loop With Break 🛑

break stops the loop immediately, even if the condition is still True.

while_break.py

i = 1

while i <= 10:
    if i == 5:
        break
    print(i)
    i += 1

Note

✔️ Loop stops when i becomes 5.

5. While Loop With Continue 🔄

continue skips the current iteration and moves to the next one.

while_continue.py

i = 0

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

Note

✔️ Skips printing the value 3.

6. While Loop With Else Block 🎯

The else block runs when the loop condition becomes False normally (no break).

while_else.py

i = 1

while i <= 3:
    print(i)
    i += 1
else:
    print("Loop completed")

7. Nested While Loops 🪜

nested_while.py

i = 1

while i <= 3:
    j = 1
    while j <= 3:
        print(i, j)
        j += 1
    i += 1

8. Using While Loop for Menus 📋

menu_example.py

choice = 0

while choice != 3:
    print("1. Say Hello")
    print("2. Say Bye")
    print("3. Exit")
    choice = int(input("Enter option: "))

    if choice == 1:
        print("Hello!")
    elif choice == 2:
        print("Bye!")
    elif choice == 3:
        print("Exiting...")
    else:
        print("Invalid choice")

9. Common Mistakes ⚠️

  • Forgetting to update the loop variable (infinite loop).
  • Using incorrect conditions.
  • Misplacing break or continue.

10. Real-World Example 🌍

real_world_example.py

attempts = 0

while attempts < 3:
    pin = input("Enter PIN: ")
    if pin == "1234":
        print("Login successful!")
        break
    else:
        print("Wrong PIN")
        attempts += 1
else:
    print("Account locked!")

Conclusion 🎉

>>“While loops give your program the power to repeat until the job is done.” 🔁

You now understand Python’s while loop thoroughly! Want the next topic? Try For Loop, Range(), Loop Control Statements, or Nested Loops. Just tell me! 😊