Exercises · T05 functions

Covers: prototypes, parameters, return values, void, pass-by-value, overloading, decomposition, reference parameters for outputs, const parameters. Lectures L13–L16, L26. Outcomes PF-7.x, PF-8.x, PF-13.x.

12 exercises · ladder 🟢 → 🔴. From E-056 on, decomposition into functions is the graded skill — a correct monolith doesn't earn full credit.

PF-E-054 · First Function

Difficulty: Beginner · Lecture: L13 · Outcomes: PF-7.1 Prerequisites: E-003 Problem: Write int square(int n) and call it from main on the values 3, 7, and −4, printing each result. Write the prototype above main and the definition below it. Input: none · Output: three squares. Sample: — → 9 / 49 / 16 Hints: prototype, call, definition — three separate locations.

PF-E-055 · Max of Three (reusing Max of Two)

Difficulty: Beginner · Lecture: L13 · Outcomes: PF-7.1, PF-7.3 Prerequisites: E-054 Problem: Write int max2(int a, int b), then write int max3(int a, int b, int c) that calls max2 twice. Read three integers and print the maximum. Input: three integers · Output: one integer. Sample: 5 9 2 → 9 Hints: max2(a, max2(b, c)) — composition is the point.

PF-E-056 · Temperature Suite

Difficulty: Foundational · Lecture: L13 · Outcomes: PF-7.1, PF-7.2 Prerequisites: E-004, E-055 Problem: Write double toFahrenheit(double c) and double toKelvin(double c). Read a Celsius temperature and print a small table (C, F, K) for that value and for 0, 25, 100. Input: one double · Output: 4 rows × 3 columns, labeled. Sample: input 37.0 → row 37.0 98.6 310.2 Hints: both functions take Celsius — no function calls another conversion.

PF-E-057 · Even/Odd/Prime Classifier Functions

Difficulty: Foundational · Lecture: L13 · Outcomes: PF-7.1, PF-7.2 Prerequisites: E-039, E-056 Problem: Write bool isEven(int), bool isOdd(int), and bool isPrime(int). Read one integer (2–1000) and print all three classifications. isOdd must call isEven. Input: one integer · Output: three words. Sample: 17 → even: no / odd: yes / prime: yes Hints: isPrime reuses your E-039 loop, wrapped in a bool return.

PF-E-058 · Multiplication-Table Generator

Difficulty: Foundational · Lecture: L13 · Outcomes: PF-7.1, PF-7.2 Prerequisites: E-029, E-057 Problem: Write void printTable(int n, int rows) that prints n × 1 … n × rows in aligned columns (width 6). main reads n and rows and calls it. Input: two integers · Output: the table. Sample: 7 5 → 7 14 21 28 35 (one per line) Hints: a void function does the printing; main does the reading — separation of I/O.

PF-E-059 · Rounding and Casting Helpers

Difficulty: Foundational · Lecture: L13 · Outcomes: PF-7.1, PF-3.2 Prerequisites: E-056 Problem: Write int roundToNearest(double x) (round half away from zero, correctly handling negatives) and double truncateTo2(double x) (truncate toward zero to 2 decimals). Demonstrate both on 2.5, -2.5, 3.14159, -3.14159. Input: none · Output: labeled results. Sample: round(2.5) = 3 / round(-2.5) = -3 / trunc2(3.14159) = 3.14 Hints: rounding: compare x - static_cast<int>(x); truncation: static_cast<int>(x * 100) / 100.0 — think about why negatives work.

PF-E-060 · Min/Max/Average with Out-Parameters

Difficulty: Intermediate · Lecture: L26 · Outcomes: PF-8.1, PF-13.3 Prerequisites: E-057, E-031 Problem: Write void stats(double a, double b, double c, double& minOut, double& maxOut, double& avgOut). Read three doubles and print the three results using the out-parameters. Also demonstrate (in comments) that a by-value version cannot deliver the same results. Input: three doubles · Output: min, max, average. Sample: 4.5 2 9 → min: 2 / max: 9 / avg: 5.17 Hints: three reference parameters; the by-value comment is part of the deliverable.

PF-E-061 · Function Overloading: area()

Difficulty: Intermediate · Lecture: L15 · Outcomes: PF-8.1 Prerequisites: E-060 Problem: Write three overloaded double area(...): circle (one double), rectangle (two doubles), triangle (base and height — same signature problem: use three doubles for triangle by Heron's formula with sides). Demonstrate each; explain in comments how the compiler picks. Input: none (fixed demonstration calls) · Output: labeled areas. Sample: — → circle r=2: 12.57 / rect 3x4: 12.00 / triangle 3-4-5: 6.00 Hints: rect vs triangle can't both be (double, double) — Heron takes three sides.

PF-E-062 · Recursive Countdown + Sum

Difficulty: Intermediate · Lecture: L16 · Outcomes: PF-8.2 Prerequisites: E-061 Problem: Write void countdown(int n) (prints n..1 then done) and long long sumTo(int n) (1+2+…+n), both recursive. Read n (1–500) and demonstrate both. Add a comment: what happens with n = 0 for each, and why? Input: one integer · Output: countdown lines, sum, note. Sample: n = 3 → 3 2 1 done / sum: 6 Hints: base case first; recursion is introduced in L16 as a concept, keep the calls shallow.

PF-E-063 · Unit Conversion Library

Difficulty: Intermediate · Lecture: L15 · Outcomes: PF-8.1, PF-8.2 Prerequisites: E-062 Problem: Build convert.cpp with functions: kmToMiles, milesToKm, kgToLbs, lbsToKg, cToF, fToC. Each validates its domain (non-negative where sensible) and returns a sentinel -1 on invalid input. main offers a small switch menu driving them. Input: menu choice + value · Output: converted value or error. Sample: choice 1, value 10 → 10 km = 6.21 miles Hints: the menu loop is do-while; conversion factors as const double.

PF-E-064 · Deadduck Debugging (fix the signatures)

Difficulty: Intermediate · Lecture: L26 · Outcomes: PF-8.1, PF-13.3 Prerequisites: E-060, E-063 Problem: You are given (in comments) five broken function designs: (1) a swap by value, (2) a "returns two values" function, (3) an array parameter with no size, (4) a read-only string taken by value, (5) a getter that prints instead of returning. For each: state the defect in one line, then write the corrected version and demonstrate it. Input: none · Output: five demonstration blocks. Sample: — → defect 1: copies cannot swap → fixed with int& … Hints: the fixes use references, split returns, size parameters, const&, and return values respectively.

Difficulty: Advanced Introductory · Lecture: L16 · Outcomes: PF-8.1, PF-8.2, PF-5.3 Prerequisites: E-063, E-064 Problem: Write a menu program: 1) circle area 2) rectangle area 3) triangle area (Heron) 4) quit. Each computation lives in its own function; input validation lives in a reusable double readPositive(const std::string& prompt); the menu loops until quit; invalid menu choices are rejected with a re-prompt (bounded to 5 bad attempts then quit). Print results with 2 decimals. Input: menu choices + values · Output: computed areas or errors. Sample: choice 1, r = 2 → 12.57; choice 9 → re-prompt. Hints: readPositive is the reusable validator — every other function assumes clean input; that division of labor is the design lesson.