结构体和指针

指向结构体变量的指针是结构体指针。

结构体的变量名不是指向结构体的地址，所以给指针赋值时，需要加上取址运算符&

int a[] = {1, 2, 3};

struct Example{
  int a;
  char b;
} example;

example = { 2, 'b'};

int *p1 = NULL;
int *p2 = NULL;
p1 = a;
p2 = &example;

调用结构体中的变量

(*p2).a = 3;

p2->a = 3;

使用结构体实现单链表添加操作

头插法


#include <stdio.h>
#include <stdlib.h>

//定义单链表一个节点
struct  Book
{
    char name[10];
    char author[10];
    struct Book *next;
};

//声明添加一个节点方法
void addBook(struct Book **libary);
//声明录入一本书的方法
void getInputBook(struct Book *book);
//声明输出链表方法
void printLibrary(struct Book *library);
//声明释放动态内存
void releaseLibrary(struct Book *library);

int main(void)
{
    struct Book *library = NULL;
    char flag;
    
    while(1){
        printf("是否需要录入图书数据，Y是，N否\n");
        do{

        flag = getchar();

        }while(flag != 'Y' && flag != 'N');

        if(flag == 'Y'){
            addBook(&library);
        }else{
            break;
        }
    }
    
    printf("是否需要打印图书数据，Y是，N否\n");
    do{

    flag = getchar();

    }while(flag != 'Y' && flag != 'N');

    if(flag == 'Y'){
        printLibrary(library);
    }

    releaseLibrary(library);
    return 0;
}

void addBook(struct Book **libary){

    struct Book *book, *temp;

    book = (struct Book *)malloc(sizeof(struct Book));

    if(NULL == book){
        printf("内存分配失败\n");
        exit(1);
    }

    getInputBook(book);

    if(libary != NULL){
        temp = *libary;
        *libary = book;
        book->next = temp;
    }else{
        *libary = book;
        book->next = NULL;
    }

}

void getInputBook(struct Book *book){

    printf("请输入书名\n");
    scanf("%s", book->name);
    printf("请输入作者\n");
    scanf("%s", book->author);

}

void printLibrary(struct Book *library){

    int count = 1;

    while(library!= NULL){
        printf("book%d\n", count);
        printf("书名:%s\n", library->name);
        printf("作者:%s\n", library->author);
        printf("========\n");
        count++;
        library = library->next;
    }

}

void releaseLibrary(struct Book **library){

    struct Book *temp;
    while(*library!=NULL){
        temp = library;
        *library = (*library)->next;
        free(temp);
    }

}

尾插法，只需要修改上面的addBook方法

void addBook(struct Book **libary){

    struct Book *book, *temp;
    static struct Book *tail;

    book = (struct Book *)malloc(sizeof(struct Book));

    if(NULL == book){
        printf("内存分配失败\n");
        exit(1);
    }

    getInputBook(book);

    if(libary != NULL){
        tail->next = book;
        book->next = NULL;
    }else{
        *libary = book;
        book->next = NULL;
    }
        tail = book;
}

对链表进行添加和删除操作

#include <stdio.h>
#include <stdlib.h>

//定义单链表一个节点
struct  Num
{
    int a;
    struct Num *next;
};

//声明添加一个节点方法
void addNum(struct Num **libary, int newNum);
//声明删除一个节点方法
void delNum(struct Num **library, int newNum);
//声明输出链表方法
void printLibrary(struct Num *library);
//声明释放动态内存
void releaseLibrary(struct Num *library);

int main(void)
{
    struct Num *library = NULL;
    int flag;
    
    do{
    printf("请输入一条数据，（-1代表终止）：");

    scanf("%d", &flag);

    if(flag == -1){
        break;
    }

    addNum(&library, flag);

    printLibrary(library);

    }while(flag != -1);


    printf("下面一个一个删除数据\n");
    do{
        printf("请输入一条数据，（-1代表终止）：");

        scanf("%d", &flag);

        if(flag == -1 || library == NULL){
            break;
        }

        delNum(&library, flag);

        printLibrary(library);

    }while(flag != -1);

    releaseLibrary(library);
    return 0;
}

void addNum(struct Num **library, int newNum){

    struct Num *num, *previous, *current;

    current = *library;
    previous = NULL;

    while(current!= NULL && (current->a  < newNum)){
            previous = current;
            current  = current->next;
    }

    num = (struct Num *)malloc(sizeof(struct Num));

    if(NULL == num){
        printf("内存分配失败\n");
        exit(1);
    }

    num->a = newNum;
    num->next = current;

    if(previous != NULL){
        
        previous->next = num;

    }else{
        *library = num;
    }

}

void delNum(struct Num **library, int newNum){

    struct Num *num, *previous, *current;

    current = *library;
    previous = NULL;

    while(current != NULL && current->a != newNum){
        previous = current;
        current = current->next;
    }

    if(current == NULL){
        printf("没有找到 %d\n", newNum);
    }else{
        //第一个就是找到的值
        if(previous==NULL){
            
            *library = current->next;

        }else{
            previous->next = current->next;
        }
        
    }


}

void printLibrary(struct Num *library){

    while(library!= NULL){
        printf("%d ", library->a);
        library = library->next;
    }
    putchar('\n');
}

void releaseLibrary(struct Num *library){

    struct Num *temp = library;

    while(temp!=NULL){
        free(library);
        library = library->next;
        temp = library;
    }

}