单链表的实现和基本操作

/* *
* File: Main.c
* Descript: 单链表操作
* Author: Red_angelX
*/

# include <stdio.h>
# define MAXNUM 100

/* *
* 学生结构体链表
* */
typedef struct student
{
    int  number ;
    char name[ 10 ];
    int score;
     // 新增链表指针
    struct student *   next ;
}student;

/* *
* 创建链表
* */
student *  create()
{
    int n , i;
    student  * head ,* preview ,* current ;     /*  head表头 preview前一个 current当前  */
     if (( head  =  (student  * )(malloc( sizeof (student))))  ==   NULL )
    {
         printf ( "          无法分配内存 " );
         exit ( 0 );
    }
    head -> next   =   NULL ;   /*  表头置空 初始化  */
    preview  =  head;      /*  preview 指向表头  */

     printf ( "            请输入学生数: " );
    scanf( " %d " ,& n);
     for (i = 0 ;i < n;i ++ )
    {
         if ((  current   =  (student  * )(malloc( sizeof (student))))  ==   NULL )
        {
             printf ( "         无法分配内存 " );
             exit ( 0 );
        }
        preview -> next   =   current ;       /* 把前一个节点指向当前节点,连接所有链表 */
         printf ( "            请输入学生%d的数据: " , i + 1 );
         printf ( "                     学号:  " );
        scanf( " %d " ,& current -> number );
         printf ( "                     姓名:  " );
        scanf( " %s " ,& current -> name);
         printf ( "                     成绩:  " );
        scanf( " %d " ,& current -> score);
         current -> next   =   NULL ;
        preview  =   current ;   
    }
     return  (head);
}

/* *
* 查找节点
* */
void find(student  * stu)
{
    int x;
    student  * head;
     printf ( "           请输入要查找学生的学号: " );
    scanf( " %d " ,& x);
    head  =  stu;

     while (head  &&  head -> number   !=  x)
    {
        head  =  head -> next ;   /* 指向下条记录  */
    }
     if (head)
    {
         printf ( "  学号   姓名   成绩 " );
         printf ( " %6d " ,  head -> number );
         printf ( "    %s " , head -> name);
         printf ( " %6d " ,  head -> score);        
    }
     else
    {
         printf ( "            没找到! " );
    }
}

/* *
*插入节点
*就当往最后插入了
* */
void insert(student  * stu)
{
    int i , n;
    student  * head ,* current ;    
     printf (            " 请插入学生数: " );
    scanf( " %d " ,& n);
    head  =  stu;
     // 把head移动到最后
     while (head -> next  )
        head = head -> next ;

     for (i = 0 ;i < n;i ++ )
    {
         if ((  current   =  (student  * )(malloc( sizeof (student))))  ==   NULL )
        {
             printf ( "         无法分配内存 " );
             exit ( 0 );
        }
        head -> next   =   current ;
         printf ( "            请输入学生%d的数据: " , i + 1 );
         printf ( "                     学号:  " );
        scanf( " %d " ,& current -> number );
         printf ( "                     姓名:  " );
        scanf( " %s " ,& current -> name);
         printf ( "                     成绩:  " );
        scanf( " %d " ,& current -> score);
         current -> next   =   NULL ;
        head  =   current ;
    }
}

/* *
* 删除节点
* */
void delete(student  * stu)
{
    int x;
    student  * head ,* temp;

     printf ( "       输入要删除成绩学生的学号: " );
    scanf( " %d " ,& x);
    head  =  stu;

     while (head -> next   &&  head -> next -> number   !=  x)
    {
        head  =  head -> next ;   /* 指向下条记录  */
    }

     if (head -> next )
    {
        temp  =  head -> next ;
        head -> next   =  head -> next -> next ;
        free(temp);
         printf ( "      已删除! " );
    }
     else
    {
         printf ( "      无此学生成绩,无法删除! " ); 
    }
}

/* *
* 主函数,链表操作
* 
* Author: Red_angelX
*/
void main()
{
    student  * stu;
    int k;
     while  ( 1 )
    {        
             // clrscr();
             printf ( "              ******************************   " );
             printf ( "             |           学生成绩管理        | " );
             printf ( "             |*******************************| " );
             printf ( "             |           1 登记成绩          | " );
             printf ( "             |           2 查询成绩          | " );
             printf ( "             |           3 插入成绩          | " );
             printf ( "             |           4 删除成绩          | " );
             printf ( "             |           0 退出程序          | " );
             printf ( "             |*******************************| " );
             printf ( "             |       Code By Red_angelX      | " );
             printf ( "               *******************************  " );
             printf ( " " );
             printf ( "             请输入选择的功能号: " );
            scanf( " %d " ,& k);
             switch (k)
            {
             case   1 :  
                stu  =  create();
                 break ;
             case   2 :
                find(stu);
                 break ;
             case   3 :  
                insert(stu);
                 break ;
             case   4 :  
                delete(stu);
                 break ;
             case   0 :   exit ( 0 );
             default : printf ( " 选择错误! " );
            }
    }
        
}