Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

#include <iostream>
#include <string>

class Rectangle {
public:
    // explicit prevents accidental implicit conversion
    explicit Rectangle(double width, double height)
        : width_(width), height_(height)   // member initialiser list
    {
        if (width_ <= 0 || height_ <= 0)
            throw std::invalid_argument("Dimensions must be positive");
    }

// const member functions promise not to modify the object
    double width()     const { return width_;          }
    double height()    const { return height_;         }
    double area()      const { return width_ * height_; }
    double perimeter() const { return 2 * (width_ + height_); }

// Mutators that enforce invariants
    void setWidth(double w) {
        if (w <= 0) throw std::invalid_argument("Width must be positive");
        width_ = w;
    }

void setHeight(double h) {
        if (h <= 0) throw std::invalid_argument("Height must be positive");
        height_ = h;
    }

void print() const {
        std::cout << "Rectangle(" << width_ << " x " << height_
                  << ")  area=" << area()
                  << "  perimeter=" << perimeter() << "
";
    }

private:
    double width_;
    double height_;
};

int main() {
    Rectangle r(5.0, 3.0);
    r.print();
    r.setWidth(10.0);
    r.print();
    return 0;
}