链表的基本操作

链表的基本操作包括建立链表、链表的插入、删除、输出和查找等。

#include < stdlib.h >
#include < stdio.h >
#include < conio.h >
#include < ctype.h >
#define  NULL 0
#define  LEN sizeof(struct student)

extern  unsigned _floatconvert;     /* 防止floating point formats not linked 错误发生 */
#pragma extref _floatconvert

typedef  struct  student    
{
     long  num;
     float  score;
     struct  student  * next;
}STU;

int  n;

STU  * CreateEnd()
{
    STU  * p1, * p2, * head;
    n = 0 ;head = NULL;
    p1 = (STU  * )malloc(LEN);         /* 创建第一个结点 */
    scanf( " %ld,%f " , & p1 -> num, & p1 -> score);
    p1 -> next = NULL;
     while (p1 -> num != 0 )         /* 将结点加入链表 */
    {
         ++ n;
         if (n == 1 )         /* 是第一个结点，作表头 */
            head = p1;
         else              /* 不是第一个结点，作表尾 */
            p2 -> next = p1;
        p2 = p1;
        p1 = (STU  * )malloc(LEN);     /* 开辟下一个结点 */
        scanf( " %ld,%f " , & p1 -> num, & p1 -> score);
        p1 -> next = NULL;
    }
    free(p1);             /* 释放最后一个结点所占的内存 */
     return  (head);             /* 返回链表的头指针 */
}
STU  * CreateStart()
{
    STU  * head, * p;
    n = 0 ;
    head = NULL;
    p = (STU  * )malloc(LEN);
    scanf( " %ld,%f " , & p -> num, & p -> score);
    p -> next = head;
     while (p -> num != 0 )
    {
         ++ n;
        head = p;
        p = (STU  * )malloc(LEN);
        scanf( " %ld,%f " , & p -> num, & p -> score);
        p -> next = head;
    }
    free(p);
     return  (head);
}
void  print(STU  * head)
{
    STU  * p;
    printf( " \nNow,These %d nodes are :\n " ,n);
    p = head;
     do
    {
        printf( " %ld\t%5.1f\n " ,p -> num,p -> score);
        p = p -> next;
    } while (p != NULL);
}

STU  * insert(STU  * head,STU  * stud)
{
    STU  * p0, * p1, * p2;
    p1 = head;             /* p1指向第一个结点 */
    p0 = stud;             /* p0指向要插入的结点 */
     if (head == NULL)             /* 原来是空表 */
    {head = p0;p0 -> next = NULL;}     /* 使p0指向的结点作为链表第一个结点 */
     else
    {
         while ((p0 -> num > p1 -> num) && (p1 != NULL))
        {p2 = p1;p1 = p1 -> next;}     /* 找插入点 */
         if (head == p1)         /* 作为表头 */
        {p0 -> next = head;head = p0;}
         else              /* 插到p2指向的结点之后 */
        {p2 -> next = p0;p0 -> next = p1;}
    }
     ++ n;
     return  head;
}

STU  * del(STU  * head, long  num)
{
  STU  * p1, * p2;
   if (head == NULL)
  {printf( " \nList null!\n " ); goto  end;}         /* 链表为空 */
  p1 = head;                     /* 从头结点开始查找 */
   while (num != p1 -> num  &&  p1 != NULL)         /* p1指向的不是所要找的结点，并且没有到表尾 */
  {p2 = p1;p1 = p1 -> next;}                 /* 后移一个结点 */
   if (num == p1 -> num)                 /* 找到需要删除的结点 */
  {
     if (p1 == head)                 /* p1指向的是头结点 */
      head = p1 -> next;             /* 第二个结点成为新的头结点 */
     else
      p2 -> next = p1 -> next;             /* 后继结点的地址赋给前一结点 */
    printf( " delete:%ld\n " ,num);
    free(p1);
    n -- ;
  }
   else
    printf( " %ld not been found!\n " ,num);
end:
   return  head;
}
STU  * find(STU  * head, long  num)
{
  STU  * p1, * p2;
   if (head == NULL)
  {printf( " \nlist null!\n " ); goto  end;}
  p1 = head;
   while (num != p1 -> num  &&  p1 != NULL)
  {p2 = p1;p1 = p1 -> next;}
   if (p1 != NULL)
    printf( " find:%ld %5.1f\n " ,num,p1 -> score);
   else
    printf( " %ld not been found!\n " ,num);
end:
   return  head;
}
void  main()
{
    STU  * head, * stu;
     long  find_num,del_num;
     char  letter;
    head = CreateEnd();
     // head=CreateStart();
    print(head);

     do
    {
        printf( " A Insert student information\n " );
        printf( " B Find student information\n " );
        printf( " C Delete student information\n " );
        printf( " Q Quit\n " );
        printf( " Please select: \n " );

        letter  =  getch();
        letter  =  toupper(letter);

         switch  (letter)
        {
         case   ' A ' :
            printf( " Please input the information of student:\n " );
            stu = (STU  * )malloc(LEN);
            scanf( " %d,%f " , & stu -> num, & stu -> score);
            head = insert(head,stu);
            print(head);
             break ;
         case   ' B ' :
            printf( " Please input the find number:\n " );
            scanf( " %ld " , & find_num);
            head = find(head,find_num);
            print(head);
             break ;
         case   ' C ' :
            printf( " Please input the delete number:\n " );
            scanf( " %ld " , & del_num);
            head = del(head,del_num);
            print(head);
             break ;
        }
    } while  (letter  !=   ' Q ' );
    getch();
}