## Challenge Overview:

You will create a function to calculate the area of a rectangle. The function must throw a custom exception, `NegativeDimensionException`, if either the width or the height provided is negative. This ensures that only valid, non-negative dimensions are used in area calculations.

**Key Points:**
- Define a custom exception class: `NegativeDimensionException`;
- Calculate the area using width and height;
- Throw the exception if width or height is negative;
- Return the area for valid dimensions.

**Example Usage:**
```cpp
try {
    int area = rectangleArea(5, -2);
    // This line will not execute because an exception is thrown
} catch (const NegativeDimensionException& e) {
    std::cout << e.what() << std::endl; // Output: Rectangle dimensions must be non-negative.
}
```


#define CATCH_CONFIG_MAIN
#include <catch2/catch.hpp>


#include <exception>
#include <string>

class NegativeDimensionException : public std::exception {
    std::string message;
public:
    NegativeDimensionException(const char* msg) : message(msg) {}
    const char* what() const noexcept override {
        return message.c_str();
    }
};

int rectangleArea(int width, int height);

TEST_CASE("rectangleArea returns correct area for positive dimensions", "[rectangleArea]") {
    REQUIRE(rectangleArea(3, 4) == 12);
    REQUIRE(rectangleArea(0, 5) == 0);
    REQUIRE(rectangleArea(7, 1) == 7);
}

TEST_CASE("rectangleArea throws NegativeDimensionException for negative width", "[rectangleArea]") {
    try {
        rectangleArea(-1, 5);
        REQUIRE(false); // Should not reach here
    } catch (const NegativeDimensionException& ex) {
        REQUIRE(std::string(ex.what()) == "Rectangle dimensions must be non-negative");
    } catch (...) {
        REQUIRE(false); // Wrong exception type
    }
}

TEST_CASE("rectangleArea throws NegativeDimensionException for negative height", "[rectangleArea]") {
    try {
        rectangleArea(5, -2);
        REQUIRE(false); // Should not reach here
    } catch (const NegativeDimensionException& ex) {
        REQUIRE(std::string(ex.what()) == "Rectangle dimensions must be non-negative");
    } catch (...) {
        REQUIRE(false); // Wrong exception type
    }
}

TEST_CASE("rectangleArea throws NegativeDimensionException for both dimensions negative", "[rectangleArea]") {
    try {
        rectangleArea(-3, -4);
        REQUIRE(false); // Should not reach here
    } catch (const NegativeDimensionException& ex) {
        REQUIRE(std::string(ex.what()) == "Rectangle dimensions must be non-negative");
    } catch (...) {
        REQUIRE(false); // Wrong exception type
    }
}

test.cpp

A practical course on mastering exception handling in modern C++. Learn how to write robust code by detecting, throwing, and managing errors using exceptions. Each section introduces a new aspect of exception handling, followed by hands-on challenges inspired by real-world scenarios.

Understand the basics of exception handling in C++. Learn about try-catch blocks, throw statements, and the standard exception hierarchy.

Learn how to define and use your own exception classes for more descriptive error handling.

Discover how to write exception-safe code and manage resources properly using RAII.

Explore advanced techniques such as exception propagation, rethrowing, and exception specifications.

Challenge: Rectangle Area Calculator

Challenge Overview:

Løsning