Summary  
Passing structs by reference to functions lets you modify the original struct’s data directly from within the function.

General domain of usage  
Data manipulation in applications

When you pass a struct **by reference** to a function, any changes made inside the function affect the **original struct**, allowing you to **modify its data directly**. This is especially useful for updating specific fields, such as changing the **`age`** of a `Person` struct.


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

struct Person {
    std::string name;
    int age;
};

void updateAge(Person& p, int newAge);

TEST_CASE("updateAge updates the age to 35", "[updateAge]") {
    Person alice{"Alice", 30};
    updateAge(alice, 35);
    REQUIRE(alice.age == 35);
}

TEST_CASE("updateAge updates the age to 0", "[updateAge]") {
    Person bob{"Bob", 25};
    updateAge(bob, 0);
    REQUIRE(bob.age == 0);
}

TEST_CASE("updateAge handles negative age", "[updateAge]") {
    Person charlie{"Charlie", 40};
    updateAge(charlie, -5);
    REQUIRE(charlie.age == -5);
}

test.cpp

Master the essentials of C++ structures and enumerations. Learn how to define, use, and combine structs and enums to model real-world data, and practice with hands-on coding tasks.

Explore the basics of structs in C++, including their syntax, initialization, and how they differ from classes.

Delve into more complex struct scenarios, including nesting and arrays.

Discover how enums provide named constants and how to use them effectively.

Challenge: Passing Structs to Functions

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