Summary  
This chapter explains how variable scopes determine where variables can be accessed within code, covering global, local, and block scopes and how scope rules affect variable lifetimes and visibility.

General domain of usage  
Web development

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

double calculateTax(double income);

TEST_CASE("Tax for $0 income should be $0.0", "[calculateTax]") {
    double result = calculateTax(0.0);
    REQUIRE(result == Approx(0.0)); // Income: 0.0, expected tax: 0.0
}

TEST_CASE("Tax for $1000 income should be $180.0", "[calculateTax]") {
    double result = calculateTax(1000.0);
    REQUIRE(result == Approx(180.0)); // Income: 1000.0, expected tax: 180.0
}

TEST_CASE("Tax for $2500 income should be $450.0", "[calculateTax]") {
    double result = calculateTax(2500.0);
    REQUIRE(result == Approx(450.0)); // Income: 2500.0, expected tax: 450.0
}

TEST_CASE("Tax for $1234.56 income should be $222.2208", "[calculateTax]") {
    double result = calculateTax(1234.56);
    REQUIRE(result == Approx(222.2208)); // Income: 1234.56, expected tax: 222.2208
}

TEST_CASE("Tax for large income $1,000,000 should be $180,000.0", "[calculateTax]") {
    double result = calculateTax(1000000.0);
    REQUIRE(result == Approx(180000.0)); // Income: 1000000.0, expected tax: 180000.0
}

TEST_CASE("Tax for fractional income $0.75 should be $0.135", "[calculateTax]") {
    double result = calculateTax(0.75);
    REQUIRE(result == Approx(0.135)); // Income: 0.75, expected tax: 0.135
}

test.cpp

Explore the world of C++ functions and delve into their fundamental concepts and practical applications. Gain proficiency in declaring, using, and optimizing functions, including parameter handling, scope management, and function overloading. Learn about recursion, templates, and lambda expression for robust C++ programming. Develop the skills to create modular, efficient, and reusable functions for real-world coding challenges.

Now it's time to dive into the world of C++ functions! Now you will learn some general concepts about functions in C++, including their definition, declaration, and usage. Discover how to declare and call functions, and gain insights into variable scopes, both local and global, for effective program design.

We will delve into specifying and using function arguments in C++ programming. Explore concepts like pass-by-value and pass-by-reference, and understand the role of default arguments; learn how to pass arrays as function arguments and become familiar with constant function arguments.

Now we will learn about how to specify the return value of a function in C++. This includes understanding the data types that functions can return, such as integers, floating-point numbers, and arrays. We will also consider function that have no return value.

Now let's delve into some additional topic in C++! We will explore function overloading, mastering the art of creating multiple functions with the same name but different parameter lists for enhanced code flexibility. Recursion is introduced, teaching the principles of recursive functions, allowing students to solve complex problems efficiently. Additionally, the section covers lambda functions, providing insights into creating concise anonymous functions/

Challenge: Understanding Variable Scopes

Example

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Challenge: Understanding Variable Scopes

Example

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