C语言结构体链式结构之有头单链表

有头单链表的一般写法

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

//数据可以单独封装
typedef struct Node {
    int data;                //数据可以是任何类型
    struct Node* next;    //指针域
}NODE,*LPNODE;
//有表头的链表, 创建表头 --> 创建结构体变量
LPNODE createHead() {
    LPNODE headNode = (LPNODE)malloc(sizeof(NODE));
    if (NULL == headNode) {
        printf("头节点内存申请失败!\n");
        return NULL;
    }
    //初始化
    //headNode->data = 0; //表头数据域无需初始化
    headNode->next = NULL;
    return headNode;
}
//创建数据节点
LPNODE createNode(int data) {
    LPNODE newNode = (LPNODE)malloc(sizeof(NODE));
    if (NULL == newNode) {
        printf("数据节点内存申请失败!\n");
        return NULL;
    }
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}
//头插
void insertByHead(LPNODE headNode,int data) {
    LPNODE newNode = createNode(data);
    newNode->next = headNode->next;
    headNode->next = newNode;
}
//尾插
void insertByTail(LPNODE headNode, int data) {
    LPNODE newNode = createNode(data);
    LPNODE curNode = headNode;
    while (curNode->next != NULL) {
        curNode = curNode->next;
    }
    curNode->next = newNode;
}
//指定插
void insertByAppoint(LPNODE headNode, int data, int pos) {
    LPNODE newNode = createNode(data);
    LPNODE curNode = headNode->next;
    while (curNode->next != NULL && --pos) {
        curNode = curNode->next;
    }
    newNode->next = curNode->next;
    curNode->next = newNode;
}
//头删
void deleteByHead(LPNODE headNode) {
    LPNODE delNode = headNode->next;
    if (NULL == delNode) {
        printf("链表为空, 删除失败!\n");
        return;
    }
    headNode->next = delNode->next;
    free(delNode);
    delNode = NULL;
}
//尾删
void deleteByTail(LPNODE headNode) {
    LPNODE curNode = headNode->next;
    LPNODE preNode = headNode;
    if (NULL == curNode) {
        printf("链表为空, 删除失败!\n");
        return;
    }
    while (curNode->next != NULL) {
        preNode = curNode;
        curNode = curNode->next; 
    }
    free(curNode);
    curNode = NULL;
    preNode->next = NULL;
}
//尾删2
void deleteByTail2(LPNODE headNode) {
    LPNODE delNode = NULL;
    LPNODE curNode = headNode;
    if (NULL == headNode->next) {
        printf("链表为空，删除失败！\n");
        return;
    }
    while (curNode->next->next != NULL) {
        curNode = curNode->next;
    }
    delNode = curNode->next;
    curNode->next = NULL;
    free(delNode);
    delNode = NULL;
}
//指定删
void deleteByAppoint(LPNODE headNode, int posData) {
    LPNODE preNode = headNode;
    LPNODE curNode = headNode->next;
    if (NULL == preNode->next) {
        printf("链表为空,无数据可以删除!\n");
        return;
    }
    //此处顺序不能变 NULL->data 会引发冲突
    while (curNode != NULL && curNode->data != posData) {
        //preNode = preNode->next;
        preNode = curNode;
        curNode = curNode->next;
    }
    if (NULL == curNode) {
        printf("未找到指定数据!\n");
        return;
    }
    else {
        preNode->next = curNode->next;
        free(curNode);
        curNode = NULL;
    }
}
//查找节点
LPNODE searchByData(LPNODE headNode, int posData) {
    LPNODE curNode = headNode->next;
    while (curNode != NULL && curNode->data != posData) {
        curNode = curNode->next;
    }
    return curNode;
}
//需要删除相同的元素
void deleteAll(LPNODE headNode, int posData) {
    while (searchByData(headNode, posData) != NULL) {
        deleteByAppoint(headNode, posData);
    }
}
//链表打印
void printList(LPNODE headNode) {
    LPNODE curNode = headNode->next;
    while (curNode != NULL) {
        printf("%d\t", curNode->data);
        curNode = curNode->next;
    }
    printf("\n");
}
int main()
{
    //头插
    printf("---- 头插 -----: \n");
    LPNODE list = createHead();
    for (int i = 0; i < 3; i++) {
        insertByHead(list, 520 + i);
        insertByHead(list, 520 + i);
    }
    printList(list);

    //尾插
    printf("---- 尾插 -----: \n");
    insertByTail(list, 1314);
    printList(list);

    //指定位置插入
    printf("---- 指定位置插入 -----: \n");
    insertByAppoint(list, 666, 3);
    printList(list);

    //头删
    printf("---- 头删 -----: \n");
    deleteByHead(list);
    printList(list);

    //尾删
    printf("---- 尾删 -----: \n");
    deleteByTail(list);
    printList(list);

    //尾删2
    printf("---- 尾删2 -----: \n");
    deleteByTail2(list);
    printList(list);

    //指定数据删除
    printf("---- 指定数据521删除 -----: \n");
    deleteByAppoint(list, 521);
    printList(list);

    //删除全部指定数据
    printf("---- 指定数据522全部删除 -----: \n");
    deleteAll(list, 522);
    printList(list);

    system("pause");
    return 0;
}