Conditions choose a branch based on an expression. Order matters when several conditions overlap, and a boundary should belong to a deliberately chosen branch.
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.
- Write the decision rules first
- Order overlapping cases
- Test boundary values
Practice task
Classify fictional scores into three ranges with an explicit invalid-input branch.
Check your result
Test the lower and upper boundary of each range and a value outside the valid domain.
A mistake to avoid
Do not add independent if statements when only one mutually exclusive outcome is intended.
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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