Summary  
This chapter explains how to declare and initialize pointers to structures in C and how to access their members using the `->` operator, demonstrated by printing the coordinates stored in a `Point` structure.  

General domain of usage  
Computational geometry

The C programming language allows you to create pointers **not only to regular data types** but also to structures (since a structure is a custom data type).

Declaration and initialization of a pointer looks like this:
```
struct <name_of_struct>
{
    <field_of_struct>;
};

struct <name_of_struct>* <name_of_pointer>;
```

If `<name_of_pointer>` is a pointer to a structure, <br>then `*(<name_of_pointer>)` is the structure itself.

To access the fields of a structure through a pointer, you must use the `->` operator.


`->` is an analogue of the structure access operator `.`

Note

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This program shows how to work with a `Point` structure that stores two coordinates, `x` and `y`. In the `main` function, a `p1` variable is created and assigned coordinate values, then a pointer to this structure is initialized. Using the `->` operator, the program accesses the structure's fields through the pointer and prints the point's coordinates to the screen.

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

struct Student {
    char name[50];
    float math;
    float physics;
    float programming;
};

bool calculateAverageAndCheck(struct Student* s);

TEST_CASE("Student passed with average above 60", "[calculateAverageAndCheck]") {
    struct Student s;
    strcpy(s.name, "Alice");
    s.math = 70;
    s.physics = 80;
    s.programming = 90;

    REQUIRE(calculateAverageAndCheck(&s) == true);
}

TEST_CASE("Student failed with average below 60", "[calculateAverageAndCheck]") {
    struct Student s;
    strcpy(s.name, "Bob");
    s.math = 40;
    s.physics = 50;
    s.programming = 55;

    REQUIRE(calculateAverageAndCheck(&s) == false);
}

TEST_CASE("Student exactly on the passing border (average = 60)", "[calculateAverageAndCheck]") {
    struct Student s;
    strcpy(s.name, "Charlie");
    s.math = 60;
    s.physics = 60;
    s.programming = 60;

    REQUIRE(calculateAverageAndCheck(&s) == true);
}

TEST_CASE("Student with mixed grades averaging just below 60", "[calculateAverageAndCheck]") {
    struct Student s;
    strcpy(s.name, "David");
    s.math = 50;
    s.physics = 60;
    s.programming = 69;

    REQUIRE(calculateAverageAndCheck(&s) == false);
}

TEST_CASE("High-performing student always passes", "[calculateAverageAndCheck]") {
    struct Student s;
    strcpy(s.name, "Emma");
    s.math = 95;
    s.physics = 88;
    s.programming = 92;

    REQUIRE(calculateAverageAndCheck(&s) == true);
}

test.cpp

Gain a solid understanding of how structs work in C, from basic definitions to advanced memory concepts. Explore how pointers interact with structured data, discover efficient ways to organize information, and build confidence by implementing real data structures such as linked lists.

Explore the fundamentals of structs, understand why they are used, and build confidence in defining, creating, and accessing structured data.

Discover how pointers interact with structs, learn why this connection matters, and master key techniques such as dynamic allocation and passing structs to functions

Gain a solid understanding of how structs are stored in memory, explore alignment and padding, and learn how unions help manage shared data efficiently.

Dive into advanced struct patterns, including nested and anonymous structs, explore practical ways to combine them with arrays, and get familiar with common data structures.

Build confidence by implementing a linked list from scratch, explore its structure, and create essential functions for adding, traversing, and managing list elements.

Math	Physics	Programming	Average	Result
85.0	55.0	60.0	66.67	✅ Passed
50.0	40.0	45.0	45.00	❌ Failed
60.0	60.0	60.0	60.00	✅ Passed

Pointers to Structs

Example

解答