学习笔记5(结构体相关内容)

一. 结构体的定义和赋值

结构体： 一系列不同类型的数据的结合
强调：类型 != 变量
结构体名代表的只是结构体类型，没有内存空间。
结构体中的成员可以单独使用

//结构体赋值方式一:
struct Student stu1 = {"ruby",22};

//结构体赋值方式二:
struct Student stu2;
strcpy(stu2.name, "ruby");
stu2.age = 22;

//结构体赋值方式三
struct Student{
    char name[20] ;
    int age ;
}lucy = {"ruby",22};

二. 结构体数组以及初始化

#include <stdio.h>

int main(int argc, const char * argv[])
{
    //方式1:
    struct Student{
        int age;
        char *name;
    }stu[3]={{22,"peter"},{33,"tom"},{23,"tiger"}};

    for (int i = 0; i < 3; i ++) {
        printf("%s\t", stu[i].name);
    }
    printf("\n");

    //方式2:
    struct Student stu1[3] ={{22,"peter"},{33,"tom"},{23,"tiger"}};
    for (int i = 0; i < 3; i ++) {
        printf("%s\t", stu1[i].name);
    }
    printf("\n");

    //方式3:
    struct Student stu2[3];
    stu2[0] = (struct Student){22,"peter1"};
    stu2[1] = (struct Student){23,"peter2"};
    stu2[2] = (struct Student){24,"peter3"};
    for (int i = 0; i < 3; i ++) {
        printf("%s\t", stu2[i].name);
    }
    printf("\n");
    return 0;
}

三. 结构体指针

struct Student(){
    char name[20];
    int age;
};
int main(){
    struct Student *stud;
    
    //这里是申请连续的 4个struct Student 类型结构体大小的内存空间
    stud = (Student *)malloc(sizeof(struct Student) * 4);
    
    //用menset函数初始化结构体数组,全部为 0 ;
    memset(stud,0,sizeof(struct Student) * 4);

    int i ;
    //遍历赋值
    for(i = 0 ; i < 4 ; i++){
        (stud + i)->age = 20 + i;
        (stud + i)->name = "ruby"; 
    }
}

四. 用结构体实现单链表

struct Node{
    int data;   //记录当前节点
    Node * next;//记录下一个节点的内存地址
};

int enqueNode(Node *head,int data){
    //申请一个新的节点,node记录的是新节点的内存地址
    Node *node = (Node *)malloc(sizeof(struct Node));
    if (node == NULL){
        return 0;
    }
    node->data = data;
    node->next = NULL;

    Node *p = head;//把传递进来的内存地址赋值给指针变量p
    while (p->next != NULL){
        p = p->next; //指针做位移操作
    }
    p->next = node;//将申请到的新的地址赋值给指针变量p的next

    return 1;
}

int main(){
    int i;
    int num = 10;
    Node *list;

    list = (Node *)malloc(sizeof(struct Node));
    list->data = 0;
    list->next = NULL;
    for (i = 0; i < num; i++){
        enqueNode(list, i+1);
    }

    while (list->next != NULL){
        printf("%d \n",list->data);
        list = list->next;
    }

    system("pause");
    return 0;
}

五. 知识点

malloc函数和calloc的区别:

//malloc函数申请到的空间,整块是连续的
list = (Node *)malloc(sizeof(struct Node));

//而calloc申请到的空间,整块有可能是不连续的
list = (Node *)calloc(10,sizeof(struct Node));