C语言实现单链表的基本操作

链表实现

1. 定义链表结点结构体

typedef struct node {
    
    
	int val;
	struct node* next;
} MyLinkedList, node;

2. 创建一个链表，即创建一个头结点

MyLinkedList* myLinkedListCreate() {
    
    
	MyLinkedList * obj = (MyLinkedList*)malloc(sizeof(node));
	obj->next = NULL;
	return obj;
}

3. 在链表首元结点之前添加一个结点，作为新的首元结点

void myLinkedListAddAtHead(MyLinkedList* obj, int val) {
    
    
	node * newNode = (node*)malloc(sizeof(node));
	newNode->val = val;
	newNode->next = obj->next;
	obj->next = newNode;
}

4. 在链表尾结点之后添加一个结点，作为新的尾结点

void myLinkedListAddAtTail(MyLinkedList* obj, int val) {
    
    
	node * newNode = (node*)malloc(sizeof(node));
	newNode->val = val;
	newNode->next = NULL;
	node* p = obj;
	while(p->next != NULL)
		p = p->next;
	p->next = newNode;
}

5. 在指定位置插入一个结点，值为val

int myLinkedListAddAtIndex(MyLinkedList* obj, int index, int val) {
    
    
	node* p = obj;
	int j = 0;
	while (p && j < index) {
    
    
		p = p->next;
		++j;
	}
	if (!p || j > index){
    
    
		printf("ERROR!\n");
		return -1;
	}
	node* newNode = (node*)malloc(sizeof(node));  // 生成新结点
	newNode->val = val;
	newNode->next = p->next;
	p->next = newNode;
	return 0;
}

6. 删除指定位置的结点

int myLinkedListDeleteAtIndex(MyLinkedList* obj, int index) {
    
    
	node* p = obj;
	int j = 0, val = 0;
	while (p->next && j < index) {
    
    
		p = p->next;
		++j;
	}
	if (!(p->next) || j > index){
    
    
		printf("ERROR!\n");
		return -1;
	}
	node* q = p->next;
	p->next = q->next;  // 删除并释放结点
	val = q->val;
	free(q);
	return val;
}

7. 获取索引号为index的节点的数值，如果索引号错误则返回-1

int myLinkedListGet(MyLinkedList* obj, int index) {
    
    
	node* p = obj->next;
	int j = 0;
	while (p && j<index) {
    
    
		p = p->next;
		++j;
	}
	if (!p || j>index){
    
    
		printf("ERROR!\n");
		return -1;
	}
	return p->val;
}

8. 释放链表

void myLinkedListFree(MyLinkedList* obj) {
    
    
	MyLinkedList * Transit;
	while(obj->next != NULL) {
    
    
		Transit = obj;
		obj = obj->next;
		free(Transit);
	}
	free(obj);
}

9. 打印链表

void showAll(MyLinkedList* obj) {
    
    
    if(obj->next == NULL) return;
    MyLinkedList *mov = obj->next;
    while(mov != NULL) {
    
    
        printf("%d ", mov->val);
        mov = mov->next;
    }
    printf("\n");
}

10. 主函数

#include <stdio.h>
#include <malloc.h>
int main() {
    
    
	
	MyLinkedList* obj = myLinkedListCreate();
	printf("初始的四个结点：");
	int i;
	for(i = 2; i < 6; i++) {
    
    
		myLinkedListAddAtTail(obj, i * i);
	}
	showAll(obj);
	
	printf("首元结点前插入：");
	myLinkedListAddAtHead(obj, 1);
	showAll(obj);
	
	printf("尾元结点后插入：");
	myLinkedListAddAtTail(obj, 36); 
	showAll(obj);

	printf("在指定坐标插入：");
	myLinkedListAddAtIndex(obj, 2, 6);
	showAll(obj);

	printf("在指定坐标删除：");
	myLinkedListDeleteAtIndex(obj, 3);
	showAll(obj);

	printf("获取指定坐标数值：%d\n", myLinkedListGet(obj, 3));

	myLinkedListFree(obj);
}

运行结果