A loop repeats work across a collection or while a condition holds. Choose the stopping condition before coding, especially for while loops.
Before you begin
Use a local Python environment and a small file or script. Read the error output carefully and keep sample records fictional.
Work through the idea
Begin with a tiny input whose answer you can calculate by hand. Write the expected result, implement the operation and compare the actual result. Add an empty or invalid input and state its handling explicitly. Keep input parsing separate from the main calculation where practical.
- Trace one iteration
- Define when the loop stops
- Accumulate a result without resetting it accidentally
Practice task
Sum positive values in a list and count how many values were included.
Check your result
Test all-negative input, an empty list and repeated values.
A mistake to avoid
Do not change the collection being traversed without understanding the resulting behavior.
Keep a review note
Save the inputs or scenario, your reasoning and the result you checked. Explain one assumption and one case that needs more work. Revise the exercise after feedback and distinguish what you demonstrated from what remains untested.
Official reference for further study
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