# 結構

## 什麼是結構 📖

之前介紹的int、char...，這些算是基本型別
而結構於他們不同，是一種複合型別
簡單來說，就是多個型別組合成一個

## 用法

### 宣告

struct 名稱
{
    名稱裡的某一個資料
    名稱裡的某一個資料
};

### 示範Code👉

#include <stdio.h>
struct bank
{
    int account;
    unsigned money;
};
int main()
{
    struct bank WU_Bank = {.account = 48763, .money = 10000000};
    printf("Ruser in Wu_Bank\n");
    printf("account is %d and has %d $",WU_Bank.account,WU_Bank.money);
    return 0;
}

### typedef用法

因為每次呼叫一個型別都要打上 struct 名稱 太冗長、麻煩
所以可以利用 typedef 來簡化

### 示範Code👉

#include <stdio.h>
typedef struct
{
    int account;
    unsigned money;
}bank;
int main()
{
    bank WU_Bank = {.account = 48763, .money = 10000000};
    printf("Ruser in Wu_Bank\n");
    printf("account is %d and has %d $",WU_Bank.account,WU_Bank.money);
    return 0;
}

### 結構陣列

運用陣列去儲存多個結構

例子：
假設我們今天有一個人的struct 那今天有三個人
就可以運用陣列去存

### 示範Code👉

#include <stdio.h>
typedef struct
{
    int age;
    char name[30];
} people;
int main()
{
    people All_Person[3] = {
        {.name = "Andy", .age = 18},
        {.name = "Amy", .age = 23},
        {.name = "Sammy", .age = 13}
    };
    printf("%5s , %d\n", All_Person[0].name, All_Person[0].age);
    printf("%5s , %d\n", All_Person[1].name, All_Person[1].age);
    printf("%5s , %d\n", All_Person[2].name, All_Person[2].age);
}

## 注意❗

### C 的 struct 是不能被賦值的
假設我們想預設每個人都是 18 歲

typedef struct
{
    int age = 18;
    char name[30];
} people;

會發現上述的程式碼出錯

### 可以將一個創好的 結構 放入另一個 結構
假設有一個銀行裡面有幾個客戶
銀行裡有客戶的帳號 跟 客戶
客戶裡有客戶的名字 跟 年齡

typedef struct
{
    int age;
    char name[30];
} People;
typedef struct
{
    People people;
    char acount[30];
} WU_Bank;

### 如果想賦於字串時
不可這樣 ❗

#include <stdio.h>
typedef struct
{
    int age;
    char name[30];
} people;
int main()
{
    people People;
    People.name = "Amy";
    return 0;
}

要利用 strcpy

#include <stdio.h>
#include <string.h> 
typedef struct
{
    int age;
    char name[30];
} people;
int main()
{
    people People;
    strcpy(People.name,"Amy");
    return 0;
}

<!-- 指標的部分就跳過-->
## 練習
[W3school](https://www.w3schools.com/c/exercise.php?filename=exercise_structs1)
[FCUOJ練習題](https://hackmd.io/@FCU1B112/HJF1N9oN6)
## codeByClass1

#include <stdio.h>
#include <string.h>

#define max 2

typedef struct
{
    char name[1000];
    int height;
    int weight;
    int age ;
} People;

typedef struct  
{
    People people[72];
    char name_class[20];
}class;

int main()
{
    class FCU112 = {.name_class =  "FCU1121", 
                    .people[0].name = "ruser",.people[0].age = 18,.people[0].weight = 100,.people[0].height = 180,
                    .people[1].name = "Winne",.people[1].age = 23,.people[1].weight = 60,.people[1].height = 170};
    printf("%s\n",FCU112.name_class);
    
    for(int i = 0; i < max; i++) {
        printf("%5s, %3d , %3d , %3d\n",FCU112.people[i].name,FCU112.people[i].age,FCU112.people[i].weight,FCU112.people[i].height);
    }
    
}

## codeByClass2

#include <stdio.h>
#include <string.h>

#define max 2

typedef struct
{
    char name[1000];
    int height;
    int weight;
    int age;
} People;

typedef struct
{
    People people[72];
    char name_class[20];
    int number;
} class;

int main()
{
    class FCU112;
    printf("Today we have many people in here");
    printf("What the class name?");
    scanf("%s", FCU112.name_class);
    printf("How many student?(72down)\n");
    scanf("%d", &FCU112.number);
    for (int i = 0; i < FCU112.number; i++)
    {
        printf("Please input infomation of student %d\n", i + 1);
        scanf("%s", FCU112.people[i].name);
        scanf("%d %d %d", &FCU112.people[i].height, &FCU112.people[i].weight, &FCU112.people[i].age);
    }
    printf("\n");
    for (int i = 0; i < FCU112.number; i++)
    {
        printf("%5s,%3d,%3d,%3d\n", FCU112.people[i].name, FCU112.people[i].age, FCU112.people[i].weight, FCU112.people[i].height);
    }
}

## 參考
[結構](https://opensourcedoc.com/c-programming/struct/)