C语言单链表实验

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

typedef struct Student
{
  int data;
  struct Student* next;
}node;

node* CreateLink(node* head)
{
  node* p = NULL;
  node* s = NULL;
  head = p;
  int cycle = 1;
  int x = 0;

   while(cycle != 0)
  {
    scanf_s( "%d", &x);
     if(x != 0)
    {
      s = (node*)malloc(sizeof(node));
      s->data = x;
       if( NULL == head)
      {
        p = s;
        head = p;
      }
       else
      {
        p-> next = s;
        p = s;
      }
    }
     else
    {
      cycle = 0;
    }
  }
  p-> next = NULL;
  return head;
}

int LenLink(node* const head)
{
  node* p = head;
  int n = 0;

   if(p == NULL)
  {
    printf( "This is a empty link.\n");
    return 0;
  }
   while(p-> next != NULL)
  {
    n++;
    p = p-> next;
  }
  return n+1;
}

void Print(node* const head)
{
  node* p = head;
   if(p == NULL)
  {
    printf( "This is a empty link.\n");
    return;
  }
   while(p-> next != NULL)
  {
    printf( "%d\n", p->data);
    p = p-> next;
  }
  printf( "%d\n", p->data);
}
node*    DelNode(node* head, int var)
{
  node* p = head;
  node* s = p;
   if( NULL == head)
  {
    printf( "This is a empty link.\n");
    return head = NULL;
  }
   else
  {
     while(p-> next != NULL)
    {
       if(p->data == var)
      {
         if(p == head)
        {
          head = p-> next;
          free(p);
          p = head;
          s = p;
        }
         else
        {
          s-> next = p-> next;
          free(p);
          p = s-> next;
        }
      }
       else
      {
        s = p;
        p = p-> next;
      }
    }
     if(p == head && p->data == var)
    {
      free(p);
      return head = NULL;
    }
     else
    {
       if(p->data == var)
      {
        s-> next = NULL;
        free(p);
        p = NULL;
      }
    }
  }
  return head;
}

node* InsNode(node* head, int i)
{
  node* p1 = head;
  node* p2 = head;
  node* s = (node*)malloc(sizeof(node));
  s->data = i;

   if( NULL == head)
  {
    printf( "This is a empty link.\n");
    head = s;
    return head;
  }
   else
  {
     while(s->data > p1->data && p1 != NULL)
    {
      p2 = p1;
      p1 = p1-> next;
    }
     if(s->data <= p1->data)
    {
       if(head == p1)
      {
        head = s;
        s-> next = p1;
      }
       else
      {
        p2-> next = s;
        s-> next = p1;
      }
    }
     else
    {
      p1-> next = s;
      s-> next = NULL;
    }
  }
  return head;
}

node* RevLink(node* head)
{
  node* p1 = head;
  node* p2 = head;
  node* p3 = head;

   if( NULL == head || NULL == head-> next)
  {
    return head;
  }
   else
  {
    p2 = p1-> next;
     while(p2)
    {
      p3 = p2-> next;
      p2-> next = p1;
      p1 = p2;
      p2 = p3;
    }
    head-> next = NULL;
    head = p1;
    return head;
  }
}

void Release(node* head)
{
  node* p = head;

   if( NULL == head)
  {
    printf( "This is a empty link.\n");
    return;
  }

   while(p-> next != NULL)
  {
    head = p-> next;
    free(p);
    p = head;
  }
  free(head);
}

int main(int argc, char* argv[])
{
  node* head = NULL;
  //创建单链表
  head = CreateLink(head);
  //打印链表长度
  printf( "Length of single link: %d\n", LenLink(head));
  //打印链表
  Print(head);
  head = DelNode(head, 5);
  //打印链表长度
  printf( "Length of single link after delete node: %d\n", LenLink(head));
  //打印链表
  Print(head);
  head = InsNode(head, 5);
  //打印链表长度
  printf( "Length of single link after insert node: %d\n", LenLink(head));
  //打印链表
  Print(head);
  head = RevLink(head);
  //打印链表长度
  printf( "Length of single link after reverse: %d\n", LenLink(head));
  //打印链表
  Print(head);
  //释放链表堆空间
  Release(head);
  return 0;
}