#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#define S_SIZE 20
typedef struct data
{
    int id;
    char name[S_SIZE];
    int grade;
}
DATA;
typedef struct NODE
{
    DATA data;
    struct NODE *link;
}
NODE;
NODE *insert_node(NODE *plist, NODE *pprev, DATA item);
NODE *search_node(NODE *plist, int input_id);
NODE *search_pprev(NODE *plist, int input_id);
NODE *delete_node(NODE *plist, NODE *pprev, NODE *pcurr);
void print_list(NODE *plist);
void destroy_list(NODE *plist);
int main()
{
    char *line = "-------------------------", c;
    NODE *p, *q, *head = NULL;
    DATA d;
    while(c != \'5\')
    {
        puts(line);
        puts("1. 추가");
        puts("2. 전체보기");
        puts("3. 검색");
        puts("4. 삭제");
        puts("5. 종료");
        puts(line);
        while((c = getch()) < \'1\' || c > \'5\');
        switch(c)
        {
            case \'1\':
            puts("입력 : 학번 이름 성적");
            scanf("%d %s %d",&d.id,d.name,&d.grade);
            q = NULL;
            p = head;
            while(p)
            {
                if(d.id < p->data.id) break;
                q = p;
                p = p->link;
            }
            head = insert_node(head, q, d);
            break;
            case \'2\':
            puts("");
            print_list(head);
            break;
            case \'3\':
            puts("검색하려는 레코드의 학번 입력");
            scanf("%d",&d.id);
            puts("");
            p = search_node(head,d.id);
            if(p == NULL)
            puts("그런 학번은 없습니다.");
            else
            {
                printf("학번 : %d\\n",p->data.id);
                printf("이름 : %s\\n",p->data.name);
                printf("성적 : %d\\n",p->data.grade);
            }
            break;
            case \'4\':
            puts("삭제하려는 레코드의 학번 입력");
            scanf("%d",&d.id);
            puts("");
            p = search_node(head,d.id);
            q = search_pprev(head,d.id);
            if(p == NULL)
            puts("그런 학번은 없습니다.");
            else
            {
                head = delete_node(head, q, p);
                puts("삭제 완료");
            }
            break;
        }
    }
    destroy_list(head);
    return 0;
}
NODE *insert_node(NODE *plist, NODE *pprev, DATA item)
{
    NODE *pnew = NULL;
    if( !(pnew = (NODE *)malloc(sizeof(NODE))) )
    {
        puts("메모리 동적 할당 오류");
        exit(1);
    }
    pnew->data = item;
    if( pprev == NULL)
    {
        pnew->link = plist;
        plist = pnew;
    }
    else
    {
        pnew->link = pprev->link;
        pprev->link = pnew;
    }
    return plist;
}
NODE *search_node(NODE *plist, int input_id)
{
    NODE *p = plist;
    while(p)
    {
        if(input_id == p->data.id) break;
        p = p->link;
    }
    return p;
}
NODE *search_pprev(NODE *plist, int input_id)
{
    NODE *p = plist, *q=NULL;
    while(p)
    {
        if(input_id == p->data.id) break;
        q = p;
        p = p->link;
    }
    return q;
}
NODE *delete_node(NODE *plist, NODE *pprev, NODE *pcurr)
{
    if( pprev == NULL)
    plist = pcurr->link;
    else
    pprev->link = pcurr->link;
    free(pcurr);
    return plist;
}
void print_list(NODE *plist)
{
    NODE *p;
    for( p=plist ; p ; p=p->link )
    {
        printf("학번 : %d\\n",p->data.id);
        printf("이름 : %s\\n",p->data.name);
        printf("성적 : %d\\n",p->data.grade);
        puts("");
    }
}
void destroy_list(NODE *plist)
{
    NODE *p = plist, *next;
    while(p)
    {
        next = p->link;
        free(p);
        p = next;
    }
}