While Loop0%
While Loop
Beginner8 min read•Updated: 2026-09-03
While Loop
A while loop repeatedly executes a block of code as long as its condition remains True.
Key Concepts & Detailed Explanation
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Code Examples & Output
Python
count = 1
while count <= 5:
print(f"Iteration #{count}")
count += 1 # Crucial: update counter!
print("Loop finished!")
Expected Output:
Output
Iteration #1
Iteration #2
Iteration #3
Iteration #4
Iteration #5
Loop finished!
Best Practices & Common Pitfalls
Always ensure the while loop's condition will eventually evaluate to False, or the program will freeze in an infinite loop.
Practice Quiz
1. What happens if a while loop's condition never becomes False?
- A) The computer shuts down
- B) It runs indefinitely (infinite loop)
- C) Python raises InfiniteError
- D) It runs 1000 times then stops
Answer: B
Explanation: It creates an infinite loop that continues until terminated by the OS (Ctrl+C).
2. Which statement increments a counter 'i' by 1 inside a while loop?
- A) i++
- B) i += 1
- C) increment(i)
- D) i =+ 1
Answer: B
Explanation: Python does not have 'i++'; use 'i += 1'.
Practice Challenge
Write a while loop that prints all even numbers between 2 and 20.
Next Lesson
For Loop
Continue learning with hands-on practice, examples, and exercises in the upcoming topic.
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| Project: Grading System | For Loop |
Practice Quiz
Test your understanding of this lesson with 1 questions. Each question has one correct answer.