Student management system

记录一段有关结构的东西，备忘。

typedef double price; //可以把已存在的数据类型换个名字。

C语言允许对相同结构类型的变量进行直接赋值。stu1 = stu2;

结构指针比如 STU *stu1, 和 int *p 一样都是占四个字节。

结构体指针访问变量的两种方式(*stu1).ID 或者 stu1->ID;

再记录一个容易忘记的东西

typedef struct node LNode, *LinkList;

LNode s1 ⇒ struct node

LinkList s2 ==> struct node * ⇒ LNode *

---

//相比较而言，感觉头插比尾插更简单!

//头插法
void CreateList(LinkList head)
{
    LinkList p;
    int num;

    while(scanf("%d", &num), num!=-1)
    {
        p = (LinkList)malloc(sizeof(LNode));

        p->data = num;
        p->next = head->next;
        head->next = p;
    }
}


//尾插法
void CreateList(LinkList head)
{
    LinkList p, rear = head;
    int; num;

    while(scanf("%d", &num), num!=-1)
    {
        p = (LinkList)malloc(sizeof(LNode));

        p->data = num
        rear->next = p;
        rear = p;
    }
    rear->next = NULL;

}

---

课设代码

---

带头结点判空表的条件 H->next == NULL
不带头结点判空表的条件 H == NULL；此时H是头指针

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

struct stud
{
    char id[13];
    char name[21];
    int score1, score2, score3;
    int sum;
    struct stud *next;
};
typedef struct stud LNode, *LinkList;
//LNode a等价于struct stud a
//LinkList p 等价于 struct stud *p

void Display();
void CreateList(LinkList head);
void PrintList(LinkList head);
void ListDelete(LinkList head);
void ListInsert(LinkList head);
void ListStaticScore(LinkList head);

int main()
{
    LinkList head;
    int select;

    head = (LinkList) malloc (sizeof(LNode));
    head -> next = NULL;

    Display();
    while(1)
    {
        scanf("%d", &select);

        switch(select)
        {
            case 1: CreateList(head);
                    break;
            case 2: ListInsert(head);
                    break;
            case 3: ListDelete(head);
                    break;
            case 4: PrintList(head);
                    printf("\n");
                    break;
            case 5: ListStaticScore(head);
                    break;
            case 0:
                    exit(0);
        }
    }
    return 0;
}

void Display()
{
    printf("\n======================================\n\n");
    printf("*欢迎进入学生管理系统 V3.0！*\n");
    printf("1: 创建列表\n");
    printf("2: 插入元素\n");
    printf("3: 删除元素\n");
    printf("4: 显示元素\n");
    printf("5: 统计\n");
    printf("0: 退出系统\n");
    printf("\nCopyright @ 2017 STU by CLAY. All rights reserved.");
    printf("\n======================================\n");
    printf("请选择菜单项: \n");
}

void CreateList(LinkList head)//尾插法
{
    printf("输入若干整数，输入 # 表示结束 \n");

    LinkList p, rear = head;

    while(1)
    {
        p = (LinkList)malloc(sizeof(LNode));
        scanf("%s", p->id);
        if(strcmp(p->id, "#") != 0)
        //if(p->id[0] != '#')
        {
            scanf("%s%d%d%d", p->name, &p->score1, &p->score2, &p->score3);
            p->sum = p->score1 + p->score2 + p->score3;
        }
        else
            break;
        rear ->next = p;
        rear = p;
    }
    rear ->next = NULL;

    printf("\n新创建的学生信息为:\n");
    PrintList(head);
}

void PrintList(LinkList head)
{
    LinkList p = head ->next;

    while(p)
    {
        printf("%s\t%s\t%d\t%d\t%d\t%d\n", p ->id, p->name, p->score1, p->score2, p->score3, p->sum);
        p = p ->next;
    }
}

void ListInsert(LinkList head)//按照ID从小到大排序
{
    printf("当前链表中学生信息为：\n");
    PrintList(head);

    LinkList p, pre = head->next, rec;//rec存的是待插入节点之前的节点，按id顺序插
    int flag = 0;

    p = (LinkList)malloc(sizeof(LNode));
    printf("\n请输入待添加学生的信息: \n");
    scanf("%s%s%d%d%d", p->id, p->name, &p->score1, &p->score2, &p->score3);
    p->sum = p->score1+p->score2+p->score3;

    while(pre)
    {
        if( strcmp(pre->id, p->id) == 0)
        {
            flag = 1;
            break;
        }
        if( strcmp(pre->id, p->id) > 0 )
        {
            flag = 0;
            break;
        }
        rec = pre;
        pre = pre->next;
    }
    if(flag == 1)
    {
        printf("学号已有，无法添加\n\n");
    }
    else
    {
        if( !pre)
        {
            rec->next =  p;
            p->next = NULL;
        }
        else
        {
              p->next = rec->next;
              rec->next = p;
        }
    }
    printf("\n链表修改后的学生信息为：\n");
    PrintList(head);
}

void ListDelete(LinkList head)
{
    printf("当前链表中学生信息为：\n");
    PrintList(head);

    LinkList p, pre=head->next, rec;
    int flag = 0;

    p = (LinkList)malloc(sizeof(LNode));
    printf("\n请输入待删除学生的学号信息:\n");
    scanf("%s", p->id);
    while(pre)
    {
        if( strcmp(p->id, pre->id) == 0)
        {
            printf("待删除学生的信息为：\n");
            printf("%s\t%s\t%d\t%d\t%d\t%d\n", pre->id, pre->name, pre->score1, pre->score2, pre->score3, pre->sum);
            flag = 1;
            break;
        }
        rec = pre;
        pre = pre->next;
    }
    if(flag == 0)
        printf("查无此号，无法删除!\n");
    else//考虑三种情况在首元节点，中间，末尾的空节点
    {
        if( pre == head->next)
        {
            head->next = pre->next;
            free(pre);
        }
        else if( pre->next != NULL)
        {
            rec->next = pre->next;
            free(pre);
        }
        else
            rec->next = NULL;
    }
    printf("\n链表修改后的学生信息为：\n");
    PrintList(head);
}

void ListStaticScore(LinkList head)
{
    printf("当前链表中学生信息为：\n");
    PrintList(head);

    printf("有不及格学生信息统计为：\n");
    LinkList pre = head->next;
    while(pre)
    {
        if( (pre->score1 < 60) || (pre->score2 < 60) || (pre->score3 < 60) )
        {
            printf("%s\t%s\t%d\t%d\t%d\t%d\n", pre->id, pre->name, pre->score1, pre->score2, pre->score3, pre->sum);
        }
        pre = pre->next;
    }
}