Integrated Introductory Programming Practice

Putting It All Together

A real program is not one concept but all of them working together. Consider a complete small task: read a list of exam scores, and report how many students passed (scored 50 or more) and the class average. Solving it exercises every idea in this unit.

A structured approach:

1. Model the data. The scores are a list of numbers; "passed" means a score $\geq 50$; the outputs are a count and an average.
2. Sketch the algorithm in pseudocode: initialize a total and a passed count to zero; loop over each score; add it to total; if the score $\geq 50$, increment passed (a conditional inside a loop); after the loop, the average is total divided by the number of scores.
3. Package repeated logic in a function — e.g. average(scores) — so it is named and reusable.
4. Handle edge cases. What if the list is empty? Dividing by zero must be guarded. What about a score of exactly 50 (the boundary of passing)?
5. Test. Try a typical list, an empty list, all-passing and all-failing lists, and a score of exactly 50.

This is the shape of nearly all beginner programming: model the data, express the logic with loops and conditionals, factor it into functions, guard the edge cases, and test. The concepts are not isolated tricks — they are the parts you assemble, every time, into a working solution.

Common pitfall: forgetting the edge cases when integrating everything. The average of an empty list divides by zero; a score of exactly 50 sits on the pass/fail boundary (is it $\geq 50$ or $> 50$?). A program that handles the typical list but crashes on the empty one is not finished — integrate the edge-case checks from the start.

A bar chart of exam scores with a horizontal accent pass line at 50; bars at or above the line flip to accent (passed) one by one while a counter tallies them, and the mean line settles at the class average.

$$\text{average} = \frac{\text{total}}{\text{count}}, \;\; \text{count} > 0$$