Summary  
This chapter demonstrates how to implement function overloading by defining multiple functions with the same name but different parameter types or counts to achieve compile-time polymorphism and cleaner code.  

General domain of usage  
Mathematical computation libraries

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

const double PI = 3.14159;

// Function declarations (to be linked with actual implementation)
double calculateArea(double length, double width);
double calculateArea(double radius);
double calculateArea(double a, double b, double c);

TEST_CASE("Circle area with radius 3 should be ~28.27431", "[calculateArea]") {
    double result = calculateArea(3.0);
    REQUIRE(result == Approx(PI * 3 * 3)); // Area = PI * r^2
}

TEST_CASE("Rectangle area 4 x 6 should be 24", "[calculateArea]") {
    double result = calculateArea(4.0, 6.0);
    REQUIRE(result == Approx(24.0)); // Area = length * width
}

TEST_CASE("Triangle area with sides 5, 4, 6 should be ~9.92157", "[calculateArea]") {
    double result = calculateArea(5.0, 4.0, 6.0);
    double s = (5 + 4 + 6) / 2.0;
    double expected = sqrt(s * (s - 5) * (s - 4) * (s - 6));
    REQUIRE(result == Approx(expected)); // Heron's formula
}

// Additional tests for coverage
TEST_CASE("Circle area with radius 0 should be 0", "[calculateArea]") {
    double result = calculateArea(0.0);
    REQUIRE(result == Approx(0.0)); // Area = 0 for radius 0
}

TEST_CASE("Rectangle area with 0 x 10 should be 0", "[calculateArea]") {
    double result = calculateArea(0.0, 10.0);
    REQUIRE(result == Approx(0.0)); // Area = 0 if any side is 0
}

TEST_CASE("Triangle area with sides 3, 4, 5 should be 6", "[calculateArea]") {
    double result = calculateArea(3.0, 4.0, 5.0);
    REQUIRE(result == Approx(6.0)); // Classic 3-4-5 triangle
}

TEST_CASE("Triangle area with invalid sides should be 0 or NaN", "[calculateArea]") {
    double result = calculateArea(1.0, 2.0, 10.0); // Impossible triangle
    if (!std::isnan(result)) {
        REQUIRE(result == Approx(0.0)); // If not NaN, should be 0
    }
}

test.cpp

Master the core principles of functions and their practical applications. Learn to declare, use, and optimize functions through topics like parameter handling, scope management, and overloading. Explore recursion, templates, and lambda expressions to build modular, efficient, and reusable code for real-world challenges.

Learn the core ideas of functions, their purpose, creation, and usage, along with how variable scopes influence program logic.

Learn to pass data into functions using value, reference, and pointer arguments. Understand default and constant parameters, and how to handle arrays and custom structures.

Discover how to return data from functions using simple, array, or custom types. Understand when to use the void type for functions with no return value.

Advance your function skills with overloading, recursion, and lambda functions to create more flexible, efficient, and modern code.

Challenge: Function Overloading Practice

Example

解答