Antwoorden — Hoofdstuk 3: Selecties (if / elif / else)

Opmerking: Code is in het Engels, met korte Nederlandse toelichting erboven of eronder.

Antwoord 1 — Basis if

• Deelbaarheid door 2 bepaalt even/odd.

n = int(input("Enter an integer: "))
if n % 2 == 0:
    print("even")
else:
    print("odd")

Antwoord 2 — Leeftijdscategorieën

• Volgorde van drempels is belangrijk: strengste eerst of van hoog naar laag.

age = int(input("Age: "))
if age < 18:
    print("minor")
elif age <= 64:
    print("adult")
else:
    print("senior")

Antwoord 3 — Rapportcijfer naar label

• Zorg dat intervallen elkaar niet overlappen en samen 0..10 afdekken.

score = float(input("Score (0-10): "))
if score < 5.5:
    label = "insufficient"
elif score < 7.0:
    label = "sufficient"
elif score < 8.5:
    label = "good"
else:
    label = "excellent"
print(label)

Antwoord 4 — Login-indicatie

• Eenvoudige en/conditie; geen echte beveiliging.

username = input("Username: ")
password = input("Password: ")
if username == "admin" and password == "secret":
    print("Welcome!")
else:
    print("Access denied")

Antwoord 5 — Korting met lidmaatschap

• Volgorde: eerst de strengere (lid + bedrag), dan de alternatieve drempel.

amount = float(input("Amount: "))
member = input("Member? (yes/no): ").strip().lower() == "yes"
if member and amount >= 100:
    discount = 0.10
elif amount >= 150:
    discount = 0.05
else:
    discount = 0.0
final_price = amount * (1 - discount)
print(f"Discount: {discount*100:.0f}%")
print(f"Final price: {final_price:.2f}")

Antwoord 6 — Truthiness en invoer (ternary)

query = input("Search query: ").strip()
msg = "Empty query" if not query else f"Searching for '{query}'..."
print(msg)

Antwoord 7 — Kettingvergelijking 10..20

x = int(input("x: "))
print(10 <= x <= 20)

Antwoord 8 — Guard clause (functie)

• Vroeg stoppen bij ongeldige weight_kg en dan per land beslissen.

def shipping_cost(country: str, weight_kg: float) -> float:
    if weight_kg <= 0:
        raise ValueError("Weight must be positive")
    if country == "NL":
        return 4.50 if weight_kg <= 2 else 6.75
    elif country == "BE":
        return 5.20 if weight_kg <= 2 else 7.40
    else:
        return 9.90

if __name__ == "__main__":
    print(shipping_cost("NL", 1.5))  # 4.50
    print(shipping_cost("BE", 3.0))  # 7.40
    print(shipping_cost("DE", 0.5))  # 9.90

Antwoord 9 — Wachtwoordsterkte-indicatie (simpel)

pwd = input("Password: ")
length = len(pwd)
if length < 6:
    label = "weak"
elif length <= 9:
    label = "medium"
else:
    label = "strong"
print(f"{label} (length={length})")

Antwoord 10 — Netto prijs met btw‑optie

amount = float(input("Amount: "))
mode = input("Type (incl/excl): ").strip().lower()
VAT = 0.21
if mode == "incl":
    net = amount / (1 + VAT)
    print(f"Net (ex VAT): {net:.2f}")
elif mode == "excl":
    gross = amount * (1 + VAT)
    print(f"Gross (incl VAT): {gross:.2f}")
else:
    print("Unknown type; use 'incl' or 'excl'.")

Uitdaging (optioneel) — Kalenderdag naar type dag

day = input("Day name: ").strip().lower()
weekend = {"saturday", "sunday"}
label = "weekend" if day in weekend else "weekday"
print(label)