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Rental Car Calculator

Calculate the total cost of a car rental with optional extras and age surcharge

Workbook 1c, p.124-125 — Project name: rental-car-calculator

In Plain English

Build a rental car cost calculator. The customer tells you when they're picking up, how many days they need, and which optional extras they want (toll tag, GPS, roadside assistance — each costs extra per day). They also give their age — drivers under 25 pay a 30% surcharge on the base car rental. At the end, show a summary of everything and the total cost.

What a Successful Run Looks Like

Run 1 — Under 25 with Options

Enter pickup date (mm/dd/yyyy): 03/15/2026 Enter number of rental days: 3 Do you want an electronic toll tag (y/n)? y Do you want a GPS (y/n)? n Do you want roadside assistance (y/n)? y Enter your age: 22 Rental Summary -------------- Pickup date: 03/15/2026 Rental days: 3 Car rental rate: $29.99 per day Options cost: $23.70 Underage driver surcharge: $26.99 Total cost: $140.66

Car: 3 x $29.99 = $89.97. Options: 3 x ($3.95 + $3.95) = $23.70. Surcharge: $89.97 x 0.30 = $26.99. Total: $140.66

Run 2 — Over 25, No Options

Enter pickup date (mm/dd/yyyy): 04/01/2026 Enter number of rental days: 5 Do you want an electronic toll tag (y/n)? n Do you want a GPS (y/n)? n Do you want roadside assistance (y/n)? n Enter your age: 30 Rental Summary -------------- Pickup date: 04/01/2026 Rental days: 5 Car rental rate: $29.99 per day Total cost: $149.95

Car: 5 x $29.99 = $149.95. No options, no surcharge. Total: $149.95

Key detail: The 30% surcharge applies only to the base car rental cost ($29.99/day x days) — it does not apply to the optional extras. Also notice that lines like "Options cost" and "Underage driver surcharge" only appear when they are relevant.
What This Exercise Practices

This exercise reinforces these concepts from Week 1:

Scanner Input if/else Final Constants String Comparison printf Formatting Common Errors
Why this matters: This is one of the most complete exercises in Week 1 — it combines multiple inputs, string comparisons for yes/no answers, conditional logic for the age surcharge, arithmetic with constants, and formatted output. Getting this one right means you can handle real-world calculator programs.
Flow Diagram
Step 1 Ask for pickup date String input
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Step 2 Ask for rental days int input
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Step 3 Ask about toll tag y/n — $3.95/day
Step 4 Ask about GPS y/n — $2.95/day
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Step 5 Ask about roadside assistance y/n — $3.95/day
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Step 6 Ask for age int input
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Step 7 Calculate car rental cost $29.99 x days
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Step 8 Calculate options cost Sum selected options x days
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Check Under 25?
Yes
Add 30% surcharge On car rental cost only
No
No surcharge Skip this step
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Step 9 Calculate total Car + options + surcharge
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Output Display summary Formatted with $

Think about which values should be final constants. How will you compare the user's y/n answers to decide which options to include?

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