CSC 1001 — Lab 7: Functions vs. No Functions — Tracing, Debugging & Testing

Intro

This lab compares two versions of the same program — one without functions, one with — to build your tracing and debugging skills. You'll then redesign a problem using functions, test it yourself, and test a partner's code.

SectionModeWhat You'll Do
UnderstandIndividualTrace, run, and debug two versions of a trip-cost calculator (with and without functions).
DoIndividual, then PartnerRedesign a Week 6 problem using functions, write your own tests, then test a partner's code.
CommunicatePartnerDiscuss your testing results and decide whether your code needs to change.
Submit: your Lab 7 Worksheet and your Lab7.ipynb notebook7.

Understand (Individual)

Below are two versions of the same program: a trip-cost calculator that charges a daily rate for a number of days and applies a 10% discount for trips of 5 days or more. Both versions contain a bug. Work through each version on your own before moving on.

Step 1 — Trace Version A (No Functions)

Read the code below line by line. Before running anything, predict the value of each variable after every relevant line executes.

# Trip Cost Calculator (Version A -- no functions)

days: int = 7
daily_rate: int = 45
total_cost: float = 0

for day in range(1, days):
    total_cost = total_cost + daily_rate

if days >= 5:
    discount: float = total_cost * 0.10
    total_cost = total_cost - discount

print("Number of days:", days)
print("Total cost after discount: $" + str(total_cost))

Record your trace and predicted output on your Lab 7 Worksheet. (The line numbers are shown in the Lab 7 Worksheet.)

Step 2 — Trace Version B (With Functions)

Now trace Version B. Because the logic is split across functions, track which function you are "inside" at each step, and pay close attention to what each function returns (or doesn't return) to the code that called it.

# Trip Cost Calculator (Version B -- with functions)

def calculate_base_cost(days, daily_rate):
    total: float = 0
    day: int
    for day in range(days):
        total = total + daily_rate
    return total

def apply_discount(total_cost, days):
    if days >= 5:
        discount: float = total_cost * 0.10
        total_cost = total_cost - discount

def main():
    days: int = 7
    daily_rate: int = 45
    total_cost: float = calculate_base_cost(days, daily_rate)
    total_cost: float = apply_discount(total_cost, days)
    print("Number of days:", days)
    print("Total cost after discount: $" + str(total_cost))

main()

Record your trace and predicted output on your worksheet. (The line numbers are shown in the Lab 7 Worksheet.)

Step 3 — Run, Compare, and Debug

Open Jupyter and run both versions.

Hint: Version A's bug affects how many times a loop runs. Version B's bug affects whether a value calculated inside a function actually makes it back out.

Step 4 — Reflect (answer in a few sentences each)

Record your answers on your Lab 7 Worksheet.

Do

Step 1 — Redesign With Functions (Individual)

Choose one of your Week 6 problems and redo it using functions and modular design:

Neither of your original Week 6 solutions used functions — Ticket Counter was built from a shuffled block of loop/if lines, and Password Attempts was solved with a single for- or while-loop version. This time work individually and rebuild your chosen problem using functions. On your Lab 7 Worksheet, produce each of the following:

Aim for functions that each do one clear job, rather than one giant function. For example:

  • Ticket Counter Problem: one function that counts child/adult tickets from a list of ages (takes the list, returns two counts), and a separate function that prints/formats the result.
  • Password Attempts Problem: one function that checks a single password attempt, and a separate function that manages the attempt loop and decides whether to print "Access granted" or "Account locked."

Step 2 — Design Your Own Tests (Individual)

Before handing your code to anyone else, design three categories of test input and record what you expect your program to do with each on your worksheet:

Run your program with all three of your own test inputs and record the actual results on your worksheet next to your predictions.

Step 3 — Reflection

Step 4 — Partner Testing

Trade code with a partner.

Communicate (Partner)

With your partner, discuss the results of your testing, then record brief answers on your Lab 7 Worksheet:

Submit: your Lab 7 Worksheet (trace tables, reflections, requirements/subtasks/pseudocode, test-case tables, and Communicate answers) and your Lab7.ipynb notebook (corrected Version A/B code and your function-based solution).