구조체(struct)

#include <iostream>
#include <cstring>
 
using namespace std;
 
 
int main()
{
    struct Person
    {
        float height;
        float weight;
        char name[10];
        short grade;
    };
 
    {
        Person person;
        person.height = 174.2f;
        person.weight = 67.8f;
        person.grade = 1;
 
        strcpy_s(person.name, 10, "David");
 
        cout << person.height << endl;
        cout << person.weight << endl;
        cout << person.grade << endl;
        cout << person.name << endl;
    }
    {
        Person person{ 174.2f,67.8f, "David", 1 };
 
        cout << person.height << endl;
        cout << person.weight << endl;
        cout << person.grade << endl;
        cout << person.name << endl;
    }
    {
        // 이름으로 초기화. C++ 2x 이상
        Person person{ .height = 174.2f, .weight= 67.8f, .name= "David", .grade=1 };
 
        cout << person.height << endl;
        cout << person.weight << endl;
        cout << person.grade << endl;
        cout << person.name << endl;
    }
    {
        // struct 를 멤버 변수로 가지기
        struct EyeSight
        {
            float left;
            float right;
        };
        struct Person
        {
            float height;
            float weight;
            char name[10];
            short grade;
            EyeSight eyeSight;
        };
 
        Person person{ 174.2f, 67.3f, "David", 1, {1.1f, 1.0f} };
 
        cout << person.height << endl;
        cout << person.weight << endl;
        cout << person.grade << endl;
        cout << person.name << endl;
        cout << person.eyeSight.left << endl;
        cout << person.eyeSight.right << endl;
 
        // 배열이 내부에 있어도 복사가 됨
        Person person1 = person;
 
        // 비교는 안 됨
        //person == person1;
    }
    {
        Person persons[5];
        persons[0].grade = 1;
 
        cout << persons[0].grade << endl; // 1
 
        Person person1 = persons[1]; // person0 은 persons[1]이 아니라 복사한 것이다.
        person1.grade = 5; // 복사본의 grade가 변경
 
        cout << person1.grade << endl;    // 5
        cout << persons[1].grade << endl; // 정의 되지 않은 행동
 
        Person &person2 = persons[2]; // 복사본이 아닌 레퍼런스(추후 배움)
        person2.grade = 5; 
 
        cout << person2.grade << endl;    // 5
        cout << persons[2].grade << endl; // 5
    }
    {
        // strcut 의 사이즈
        struct Person0
        {
            float height;   // 4
            float weight;   // 4
            char name[10];  // 10
            short grade;    // 2
        };
        cout << sizeof(Person0) << endl;
        // height, weight, name, grade
        //   4   ,   4   ,  10 ,   2
 
        struct Person1
        {
            float height;   // 4
            short grade;    // 2
            float weight;   // 4
            char name[10];  // 10
        };
        cout << sizeof(Person1) << endl;
        // height, grade, weight, name
        //    4  ,  2(2),    4  ,  10  (2)  = 24
        
        struct alignas(16) Person2
        {
            float height;   // 4
            short grade;    // 2
            float weight;   // 4
            char name[10];
        };
        cout << alignof(Person0) << endl;
        cout << alignof(Person1) << endl;
        cout << alignof(Person2) << endl;
    }
}