c语言实现数据结构中的链表源代码

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

typedef struct LNode *List;
struct LNode {
	int data;
	List next;
};
struct LNode L;

List InitList(List PtrL) {
	PtrL = (List) malloc(sizeof(L));
	PtrL->next = NULL;
	return PtrL;
}

List CreateFromHead(List PtrL, int x) {			//头插法创建链表，最先创建的元素为链表尾 
	List s;
	s = (List) malloc (sizeof(L));
	s->data = x;
	s->next = PtrL->next;
	PtrL->next = s;
	return PtrL;
}

List CreateFromTail(List PtrL) {			//尾插法创建链表
	List s, r;
	int a[20], n;
	r = PtrL;
	printf("请输入要创建链表元素的个数："); 
	scanf("%d", &n);
	printf("请输入要创建链表元素的值："); 
	for(int i = 0; i < n; i++)
	{
		scanf("%d", &a[i]);
		s = (List) malloc (sizeof(L));
		s->data = a[i];
		s->next = r->next;
		r->next = s;
		r = s;	
	}
	return PtrL;
}

int Length(List PtrL) {
	List p;
	int i = 0;
	p = PtrL->next;
	while(p) {
		i++;
		p = p->next;
	}
	return i;
}

List FindKth(List PtrL, int k) {	//查找链表中第k个节点 
	List p = PtrL;
	int i = 0;
	while(p != NULL && i < k) {
		p = p->next;
		i++;
	}
	if(i == k) return p;
	else return NULL;
}

List Insert(List PtrL, int i, int x) {
	List p, s;
	if(i == 1) {
		s = (List) malloc(sizeof(L));
		s->data = x;
		s->next = PtrL;
		return s;
	}
	p = FindKth(PtrL,i-1);
	if(p == NULL) {
		printf("参数i错");
		return NULL; 
	}
	else {
		s = (List) malloc(sizeof(L));
		s->data = x;
		s->next = p->next;
		p->next = s;
		return PtrL;
	}

}

List Delete(List PtrL, int i) {
	List p, s;
	if(i == 1) {
		s = PtrL;
		if(PtrL != NULL) PtrL = PtrL->next;
		else return NULL;
		free(s);
		return PtrL;
	}
	p = FindKth(PtrL,i-1);
	if(p == NULL) {
		printf("第%d个结点不存在",i-1);
		return NULL;
	}
	else if(p->next == NULL) {
		printf("第%d个结点不存在",i);
		return NULL;
	}
	else {
		s = p->next;
		p->next = s->next;
		free(s);
		return PtrL;
	} 
}


void print(List PtrL) {
	List start;
	for(start = PtrL->next; start != NULL; start=start->next)
	printf("%d ",start->data);

}


int main() {
	List list, s;
	int n, m;
	list = InitList(list);
	list = CreateFromTail(list);			//取决你用头插法创建链表还是尾插法创建链表，为了让输出看着简单点，插入和删除我就直接写死了 
	printf("使用尾插法创建链表为：");
	print(list);
	printf("\n");
	list = Insert(list,3,9);
	printf("插入元素后的链表为：");
	print(list);
	printf("\n");
	m = Length(list);
	printf("链表的长度的为：%d", m);
	printf("\n");
	Delete(list,2);
	printf("删除结点后的链表为：");
	print(list);
	printf("\n");
	m = Length(list);
	printf("删除结点后的链表长度为：%d", m);
	printf("\n");
	s = FindKth(list,3);
	printf("您查找的节点值为：%d", s->data);
	return 0;
}