利用链表实现的超简单学生系统-增删查（C语言）

主要是为了熟悉链表的使用，写出来的。
废话不多说，直接上源码:

#include 
#include 
struct student
{
    int id;
    char name;
    char sex;
    char age;
    struct student *next;
};
typedef struct student st;

void show();
int get_choose();
void show_all_students(st *head);
int sum_student(st *head);
void insert_student(st *head);
void del_student(st *head);
void select_student(st *head);
st *p_head;


int main() {
    int choose;
    p_head = (st *) malloc(sizeof(st));
    p_head -> next = NULL;
    while(1)
    {
        show();
        choose = get_choose();
        switch (choose)
        {
            case 1:show_all_students(p_head);break;
            case 2:insert_student(p_head);break;
            case 3:del_student(p_head);break;
            case 4:select_student(p_head);break;
            case 5:break;
            default:break;
        }
        if(choose == 5)
        {
            break;
        }
    }
    return 0;
}

void show()
{
    puts("请选择你的操作：n1.显示是所有学生信息n2.插入学生信息n3.删除学习信息n4.搜索学生信息n5.结束系统n");
}

int get_choose()
{
    int choose_item = 0;
    printf("----------------------你选择的操作是:----------------------n");
    scanf("%d",&choose_item);
    if(choose_item>=1 && choose_item<=5)
    {
        return choose_item;
    }
    else
    {
        puts("----------------------输入有误，退出程序----------------------n");
        return (7);
    }

}

void show_all_students(st *head)
{
    st *p;
    p = head -> next;
    int count = 0;
    while(p)
    {
        if(count == 0)
        {
            puts("账号t姓名t性别t年龄n");
        }
        printf("id:%dtname:%ctsex:%ctage:%dn", p->id, p->name, p->sex,p ->age);
        count ++;
        p = p -> next;
    }
    if(count == 0)
    {
        puts("----------------------无学生信息----------------------n");
        return;
    }
    puts("----------------------以上是所有学生信息----------------------");
}

int sum_student(st *head)
{
    int count;
    st *p;
    p = head -> next;
    count = 0;
    while(p) {
        count++;
        p = p->next;
    }
    return count;
}

void insert_student(st *head)
{
    int pos,count;
    count = sum_student(head)+1;
    puts("----------------------输入你想要插入的位置----------------------n");
    printf("----------------------范围在1~%d----------------------n",count);
    scanf("%d",&pos);
    if(pos< 1 || pos>count)
    {
        puts("----------------------输入错误，请重新输入！----------------------n");
    }
    else {
        st *new;
        new = (st *) malloc(sizeof(st));
        if (new != NULL) {
            puts("----------------------请输入学生信息----------------------");
            scanf("%d %c %c %s", &new->id, &new->name, &new->sex, &new->age);
        }
        st *p_front;
        p_front = head;
        for (int i = 1; i < pos; ++i) {
            p_front = p_front->next;
        }
        st *temp;
        temp = p_front->next;
        p_front->next = new;
        new->next = temp;
    }
}
void del_student(st *head)
{
    int count,pos;
    count = sum_student(head);
    if(count == 0)
    {
        puts("----------------------无学生信息，操作无效----------------------n");
    }
    else
    {
        printf("目前数据库内存有的学生资料一共有：%dn",count);
        puts("请输入你要删除的学生资料：");
        scanf("%d",&pos);
        st *p_front;
        p_front = head;
        for (int i = 1; i < pos; ++i) {
            p_front = p_front -> next;
        }
        st *temp;
        temp = p_front -> next;
        p_front -> next = temp -> next;
        free(temp);
        puts("----------------------删除成功----------------------");
    }

}

void select_student(st *head)
{
    int pos,id,a = 0;
    pos = sum_student(head);
    if(pos == 0)
    {
        puts("----------------------无学生信息，操作无效----------------------n");
    }
    else {
        printf("目前数据库一共有：%d样本。n请输入你要搜索的学生id：", pos);
        scanf("%d", &id);
        st *p;
        p = head->next;
        while (p) {
            if (id == p->id) {
                printf("id:%dtname:%ctsex:%ctage:%dn", p->id, p->name, p->sex, p->age);
                a = 1;
                puts("----------------------以上是所有学生信息----------------------n");
                break;
            }
            p = p -> next;
        }
        if(a == 0)
        {
            puts("----------------------数据库内查无此人。----------------------n");
        }
    }
}