Rectangle Class

Write a Rectangle class.

Rectangle(width, height)

• __init__(self, width, height) — stores both as attributes.
• area(self) — returns width * height.
• perimeter(self) — returns 2 * (width + height).
• __str__(self) — returns "WIDTHxHEIGHT", e.g. "4x5" for a 4-by-5 rectangle. This is called automatically by str(rect) and print(rect).

Examples

r = Rectangle(4, 5)
r.area()        // → 20
r.perimeter()    // → 18
str(r)            // → "4x5"

Walkthrough

Thinking it through

class Rectangle:
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def area(self):
        return self.width * self.height

    def perimeter(self):
        return 2 * (self.width + self.height)

    def __str__(self):
        return f"{self.width}x{self.height}"

area and perimeter are the same formulas from Rectangle Area back in the basics section — the only difference is they now read self.width/self.height (the object's own stored attributes) instead of taking width/height as parameters directly. That's the core shift this section is about: instead of passing the same values into every function that needs them, you store them once on the object, and every method reaches for self.whatever to get at them.

__str__ is the dunder method from the lesson — you never call rect.__str__() yourself; Python calls it automatically whenever something needs a string representation of the object, most commonly str(rect) or print(rect). Without defining __str__, print(rect) would show something unhelpful like <Rectangle object at 0x...> — a memory address, not useful information about the rectangle itself.

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