C程序设计-链表操作[11.1]

文件:	链表操作.rar
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   学习C程序，我们在结构体中，我们会学到链表。也就是用指针将一个一个的结构体串起来。我根据谭浩强编写的《C程序设计》将整个程序进行了组织，可以初始化链表，添加，删除，展示链表的元素。代码如下：

 

#include <stdio.h>
#define LEN sizeof(struct student)

int n = 0; //全局变量，链表元素的总数

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

int listmenu();
struct student *input();
long input_delvalue();
struct student *create();
void print(struct student *);
struct student *del(struct student *,long);
struct student *insert(struct student *,struct student *);
int main(int argc, char *argv[])
{
    struct student *head = NULL;
    int item;
    do
    {
       item = listmenu();
       switch(item)
       {
           case -1:
                break;
           case 0:
              item = listmenu();
              break;
           case 1:
                head = create();
                break;
           case 2:
                head = insert(head,input());
                break;
           case 3:
                head = del(head,input_delvalue());
                break;
           case 4:
                print(head);
                break;
           default:
               break;
       }
    }while(-1 != item);
    system("pause");
    return 0;
}

struct student *create()
{
       n = 0;
       struct student *head;
       struct student *p1,*p2;
       
       head = NULL;
       do
       {
          p1 = input();
          if (p1->num == 0)
          {
             break;
          }
          n += 1;
          if (1 == n)
          {
            head = p1;
          }
          else
          {
             p2->next = p1;
          }
          p2 = p1;
          
       }while (1);
       p2->next = NULL;
       return head;
}

void print(struct student *head)
{
     struct student *p;
     if (0 == n)
     {
        printf("not element!\n");
        return;
     }
     else
     {
       printf("\nnow,these %d records are :\n",n);
       p = head;
       if (head != NULL)
       {
          do
          {
            printf("%ld,%5.1f\n",p->num,p->score);
            p = p->next;
          }while (p != NULL);
       }
     }
}

struct student *del(struct student *head,long num)
{
       struct student *p1,*p2;
       if (head == NULL)
       {
          printf("list is NULL!\n");
          return head;
       }
       p1 = head;
       while(num != p1->num && p1->next != NULL)
       {
           p2 = p1;
           p1 = p1->next;
       }
       if (num == p1->num)
       {
          if (p1 == head)
          {
             head = p1->next;
          }
          else
          {
              p2->next = p1->next;
          }
          printf("delete :%ld\n",num);
          n -= 1;
       }
       else
       {
           printf("%ld not been found!\n",num);
       }
       return head;
}

struct student *insert(struct student *head,struct student *stu)
{
       
       struct student *p0,*p1,*p2;
       p1 = head;
       p0 = stu;
       if(NULL == head)
       {
               head = p0;
               p0->next = NULL;
               
       }
       else
       {
           while (p0->num > p1->num && p1->next != NULL)
           {
                 p2 = p1;
                 p1 = p1->next;
           }
           if (p0->num <= p1->num)
           {
              if (p1 == head)
              {
                 head = p0;
              }
              else
              {
                  p2->next = p0;
              }
              p0->next = p1;
           }
           else
           {
               p1->next = p0;
               p0->next = NULL;
           }
       }
       n += 1;
       return head;
}

struct student *input()
{
    struct student *p;
    p = (struct student *)malloc(LEN);
    printf("please input data(num,score):\n");
    scanf("%ld,%f",&p->num,&p->score);
    return p;
}

long input_delvalue()
{
    printf("pleaes input delete student num:");
    long num;
    scanf("%ld",&num);
    return num;
}

int listmenu()
{
    int item;
    do
    {
      printf("MENU\n\n");
      printf("1\tinit link table\n");
      printf("2\tadd element\n");
      printf("3\tdelete element\n");
      printf("4\tlist element\n");
      printf("0\treturn system menu\n");
      printf("-1\texit\n");
      printf("\nyou select:");
      scanf("%d",&item);
    }while(item > 4 || item < -1);
    return item;
}