While Loops

Use a while loop to repeat a block of code as long as a condition is true. This is useful when you do not know in advance how many iterations you need.

Syntax

while condition:
    # code block

Example

total = 0
counter = 1
n = 5

while counter <= n:
    total += counter
    counter += 1

print(total)  # 15

while ... else

The else block runs only if the loop finishes without a break.

counter = 0

while counter < 3:
    print("Loop")
    counter += 1
else:
    print("Done")

Common Pitfalls

• Forgetting to update the loop variable (infinite loop).

• Using a while loop where a for loop is clearer.

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