C语言数据结构——单链表的增删改查

注意： LinkList L 于 LinkList &L 的区别，前者只能改变指针指向的内容，后者同时还可以修改指针本身，即指针内部

#include
#include
#include
typedef int ElemType;
typedef int Status;
//定义结构体
typedef struct LNode
{
 ElemType data;
 struct LNode *next;
}LNode, *LinkList;

//建立单链表
LinkList CreateList(int n)
{
 LinkList L = (LinkList)malloc(sizeof(LinkList));	//建一个头结点并初始链表
 L->next = NULL;
 int x, i;
 LinkList r = L;
 printf("input %d value:", n);
 for (i = 0; i < n; i++)
 {
  scanf_s("%d", &x);
  LinkList p = (LinkList)malloc(sizeof(LinkList));
  p->data = x;
  p->next = NULL;
  r->next = p;
  r = r->next;
 }
 return L;
}

//查找第i个元素并赋给e
Status GetElem_L(LinkList &L, int i, ElemType &e)
{
 LinkList p = L->next;
 int j = 1;
 while (p&&j < i)
 {
  p = p->next;
  ++j;
 }
 if (!p || j > i)
  return 0;
 e = p->data;
 return 1;
}

//在第 i 个位置插入 e 
Status InsertList(LinkList &L, int i, ElemType e)
{
 LinkList p = L;
 int j = 0;
 while (p&&j < i - 1)
 {
  p = p->next;
  ++j;
 }
 if (!p || j > i - 1)
  return 0;
 LinkList s = (LinkList)malloc(sizeof(LNode));
 s->data = e;
 s->next = p->next;
 p->next = s;
 return 1;
}

//删除第 i 个位置的元素，并将值保存于 e
Status DeleteList(LinkList &L, int i, ElemType &e)
{
 LinkList p = L;
 int j = 0;
 while (p->next&&j < i - 1)
 {
  p = p->next;
  ++j;
 }
 if (!(p->next) || j > i - 1)
  return 0;
 LinkList q = p->next;
 p->next = q->next;
 e = q->data; 
 free(q);	//注意一定要释放内存空间
 return 1;
}

//输出单链表
void Output(LinkList L)
{
 LinkList p = L->next;
 printf("output element:\n");
 for (; p != NULL; p = p->next)
 {
  printf("%d ", p->data);
 }
 printf("\n");
}

//主函数
int main()
{
 LinkList L;
 int n,i;
 ElemType e;
 printf("enter the length of the list:");
 scanf_s("%d", &n);
 L = CreateList(n);
 Output(L);		//输出单链表
 printf("enter the number you want to find:");	//查找
 scanf_s("%d", &i);
 GetElem_L(L, i, e);
 printf("the %d number is %d\n", i, e);
 printf("please enter the number and element you want to insert:");	//插入
 scanf_s("%d %d", &i, &e);
 InsertList(L, i, e);
 Output(L);
 printf("please enter the number and element you want to delete:");	//删除
 scanf_s("%d %d", &i, &e);
 DeleteList(L, i, e);
 Output(L);
 system("pause");
 return 0;
}