04-01: Exercises — Functions¶

Notes reference: 04-01: Functions — Basics

Q1: Define and call¶

Write a function greet(name) that returns "Hello, <name>!". Call it with two different names.

Solution

def greet(name):
    return f"Hello, {name}!"

print(greet("Jahid"))      # Hello, Jahid!
print(greet("Amelia"))     # Hello, Amelia!

Q2: Default arguments¶

Write a function power(base, exponent=2) that returns base ** exponent. Call it with and without the second argument.

Solution

def power(base, exponent=2):
    return base ** exponent

print(power(5))       # 25  (uses default exponent=2)
print(power(2, 10))   # 1024
print(power(3, 3))    # 27

Q3: Keyword arguments¶

Write a function describe_city(city, country="Bangladesh") and call it with and without the keyword argument.

Solution

def describe_city(city, country="Bangladesh"):
    return f"{city} is in {country}."

print(describe_city("Dhaka"))                     # Dhaka is in Bangladesh.
print(describe_city("Berlin", country="Germany")) # Berlin is in Germany.
print(describe_city(country="USA", city="New York"))  # keyword order doesn't matter

Q4: *args — variable positional arguments¶

Write a function total(*amounts) that returns the sum of any number of numeric arguments.

Solution

def total(*amounts):
    return sum(amounts)

print(total(10, 20))             # 30
print(total(5, 15, 25, 35))      # 80
print(total(100))                # 100

Q5: **kwargs — variable keyword arguments¶

Write a function profile(**info) that prints each key-value pair from the keyword arguments.

Solution

def profile(**info):
    for key, value in info.items():
        print(f"  {key}: {value}")

profile(name="Jahid", city="New York", role="Researcher")
# name: Jahid
# city: New York
# role: Researcher

Q6: Docstring¶

Write a function bmi(weight_kg, height_m) with a complete docstring describing parameters and return value.

Solution

def bmi(weight_kg, height_m):
    """
    Calculate Body Mass Index.

    Parameters:
        weight_kg (float): Body weight in kilograms
        height_m  (float): Height in metres

    Returns:
        float: BMI value rounded to 1 decimal place
    """
    return round(weight_kg / height_m ** 2, 1)

print(bmi(70, 1.75))   # 22.9
help(bmi)

Q7: Scope — local vs global¶

Predict the output, then verify:

x = "global"

def show():
    x = "local"
    print(x)

show()
print(x)

Solution

local
global

The x inside show() is a new local variable. The global x is unchanged.

Q8: Functions calling functions¶

Write rect_area(w, h) and rect_perimeter(w, h), then write rect_info(w, h) that calls both and returns a formatted string.

Solution

def rect_area(w, h):
    return w * h

def rect_perimeter(w, h):
    return 2 * (w + h)

def rect_info(w, h):
    return f"Rectangle {w}×{h}: area={rect_area(w, h)}, perimeter={rect_perimeter(w, h)}"

print(rect_info(4, 6))   # Rectangle 4×6: area=24, perimeter=20

Q9: Lambda¶

Write a lambda that squares a number, and a lambda that returns the larger of two values. Assign each to a variable.

Solution

square  = lambda x: x ** 2
larger  = lambda a, b: a if a > b else b

print(square(7))          # 49
print(larger(12, 9))      # 12

Q10: Functions as values (first-class)¶

Write a function apply(func, value) that takes a function and a value and returns func(value). Pass abs, str, and a custom function to it.

Solution

def apply(func, value):
    return func(value)

print(apply(abs, -15))          # 15
print(apply(str, 42))           # '42'
print(apply(lambda x: x**3, 4)) # 64

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