Strengthen your Python while loop concepts with comprehensive review questions and answers. Cover syntax, infinite loops, break, continue, pass, else clause, and common patterns.
i = 1
while i < 10:
print(i)
i += 2
i = 0
while i < 5:
print(i)
i += 1
else:
print("Done")
x = 10
while x > 0:
print(x)
x -= 2
count = 0
while count < 3:
print(count)
count += 1
0 1 2
A Python while loop repeatedly executes a block of code as long as its condition remains True. The basic syntax is: `while condition:` followed by an indented block of code. The loop continues until the condition evaluates to False or a break statement is encountered.
["Basic loop: `count = 0`\n`while count < 5: print(count); count += 1`", "Infinite loop: `while True: print('Running...')`"]
📘 Related Topics:
To prevent infinite loops: 1. Ensure the loop condition will eventually become False 2. Include a way to modify the condition variable within the loop 3. Use break statements with clear exit conditions 4. Consider adding a maximum iteration count as a safeguard
["Safe counter: `max_attempts = 3`\n`attempts = 0`\n`while attempts < max_attempts: ...`", "User input exit: `while True: if input('Quit? ') == 'y': break`"]
📘 Related Topics:
A Python while loop repeatedly executes a block of code as long as its condition remains True. The basic syntax is: `while condition:` followed by an indented block of code. The loop continues until the condition evaluates to False or a break statement is encountered.
["Basic loop: `count = 0`\n`while count < 5: print(count); count += 1`", "Infinite loop: `while True: print('Running...')`"]
📘 Related Topics:
To prevent infinite loops: 1. Ensure the loop condition will eventually become False 2. Include a way to modify the condition variable within the loop 3. Use break statements with clear exit conditions 4. Consider adding a maximum iteration count as a safeguard
["Safe counter: `max_attempts = 3`\n`attempts = 0`\n`while attempts < max_attempts: ...`", "User input exit: `while True: if input('Quit? ') == 'y': break`"]
📘 Related Topics:
def countdown(n):
while n > 0:
print(n)
n += 1 # Problem here
print("Blastoff!")
The loop runs infinitely because: 1. The condition `n > 0` remains always true since `n` is incremented (`n += 1`) instead of decremented 2. For any positive starting `n`, the value keeps increasing forever To fix it, change `n += 1` to `n -= 1` to create a proper countdown.
📘 Related Topics:
Use while loops when: - You don't know the number of iterations in advance - You need to loop until a condition changes - You're waiting for external events (e.g., user input) Use for loops when: - You need to iterate over a known sequence - You need a specific number of iterations - You're processing each item in a collection
["while: `while server_is_running: process_requests()`", "for: `for item in collection: process(item)`"]
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The else clause in while loops: - Executes only if the loop condition becomes False (normal termination) - Does not execute if the loop exits via break - Useful for search loops where you want to handle both found and not-found cases - Provides cleaner alternative to flag variables
["Search loop: `while items: item = items.pop()`\n`if match(item): break`\n`else: print('Not found')`"]
📘 Related Topics:
Common while loop patterns: 1. Counters: Initialize variable, condition checks limit, increment in loop 2. Input validation: Loop until valid input received 3. Event loops: while True with break conditions 4. Sentinel values: Loop until special value encountered
["Counter: `count = 0`\n`while count < 10: print(count); count += 1`", "Input: `while True: age = input('Age? ')`\n`if age.isdigit(): break`", "Event: `while not shutdown_event.is_set(): process_events()`"]
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