单向链表记录学生信息问题？

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NULL 0
 
struct student
{
    char name[20];
    int num;
    char sex;
    float score;
    struct student *next;
};
 
struct student *head = NULL;
 
//函数声明
void board();//界面
struct student *creat();//创建节点
void add();//添加学生信息
void add_tou();//从头插入
void add_wei();//从尾插入
void add_any();//插入指定位置
 
void delete_stu();//删除学生信息
void delete_name();//按姓名查找删除
void delete_num();//按学号查找删除
 
void find();//查找学生信息
void find_name();//按姓名查找
void find_num();//按学号查找
void display_all();//显示所有学生信息
 
struct student *save(struct student *head);//保存链表数据到文件
struct student *read();//从文件读取链表
 
int main()
{
    int choice = -1;
    do
        {  
            board();
            printf("请选择功能(0-7):\n");
            scanf("%d",&choice);
            switch(choice)
            {
                case 1: creat();break;
                case 2: add();break;
                case 3: delete_stu();;break;
                case 4: find();break;
                case 5: display_all();break;
                case 6: save(head);break;
                case 7: read();break;
                case 0: exit(0);break;
                default :break;
            }
        }while(choice);
 
    return 0;
}
 
 
void board()//界面
{
    printf("\t\t\t\t学生信息系统\n\n");
    printf("\t\t\t1.创建学生信息链表\n\t\t\t2.添加学生信息\n");
    printf("\t\t\t3.删除学生信息\n\t\t\t4.查找学生信息\n");
    printf("\t\t\t5.显示所有学生信息\n\t\t\t6.保存链表数据到文件\n");
    printf("\t\t\t7.从文件读取链表\n\t\t\t0.退出\n");
}
 
struct student *creat()//创建节点
{
    struct student *p1,*p2;
    int i,count;
    printf("输入几个学生信息？\n");
    scanf("%d",&count);
    p1=p2=(struct student*)malloc(sizeof(struct student));
    printf("请输入学生姓名 学号 性别 成绩\n");
    scanf("%s %d %c %f",p1->name,&p1->num,&p1->sex,&p1->score);
    fflush(stdin);
    head=p1;
    for(i=1;i<count;i++)
    {
        p1=(struct student*)malloc(sizeof(struct student));
        scanf("%s %d %c %f",p1->name,&p1->num,&p1->sex,&p1->score);
        fflush(stdin);
        p2->next=p1;
        p2=p1;
    }
    p2->next=NULL;
    return head;
}
 
void add()//添加学生信息
{
    int choice = -1;
    printf("请选择添加位置：1.从头插入 2.从尾插入 3.插入指定位置 0.取消\n");
    scanf("%d",&choice);
    switch(choice)
    {
        case 1: add_tou();break;
        case 2: add_wei();break;
        case 3: add_any();break;
        case 0: break;
        default: add();break;
    }
}
void add_tou()//从头插入
{
    struct student *pnew;
    pnew = (struct student*)malloc(sizeof(struct student));
    printf("请输入需添加的学生姓名 学号 性别 成绩：\n");
    scanf("%s %d %c %f",pnew->name,&pnew->num,&pnew->sex,&pnew->score);
    pnew->next = head;
    head = pnew;
}
 
void add_wei()//从尾插入
{
    struct student *pnew,*pold;
    pnew = (struct student*)malloc(sizeof(struct student));
    printf("请输入需添加的学生姓名 学号 性别 成绩：\n");
    scanf("%s %d %c %f",pnew->name,&pnew->num,&pnew->sex,&pnew->score);
    pold = head;
    while(pold->next != NULL)
        pold = pold->next;
    pold->next = pnew;
    pnew->next = NULL;
}
 
void add_any()//插入指定位置
{
    int weizhi,i;
    struct student *pnew,*pold;
    pnew = (struct student*)malloc(sizeof(struct student));
    printf("请输入需添加的学生姓名 学号 性别 成绩：\n");
    scanf("%s %d %c %f",pnew->name,&pnew->num,&pnew->sex,&pnew->score);
    printf("请输入需插入的位置：");
    scanf("%d",&weizhi);
    pold = head;
    for(i=0;i<weizhi-2;i++)
    {
        pold = pold->next;
        if(pold->next == NULL)   //如位置超出人数 则插在队尾
            break;
    }
    pnew->next = pold->next;
    pold->next = pnew;
}
 
void delete_stu()//删除学生信息
{
    int choice = -1;
    if(head == NULL)
        printf("无学生信息!\n");
    else
    {
        printf("选择删除方式: 1.按姓名查找删除 2.按学号查找删除 0.取消\n");
        scanf("%d",&choice);
        switch(choice)
        {
            case 1: delete_name();break;
            case 2: delete_num();break;
            case 0: break;
            default:delete_stu();break;
        }
    }
}
 
void delete_name()//按姓名查找删除
{
    struct student *p1,*p2;
    char find_name[20];
    int count = 0;
    printf("请输入需删除的学生姓名：");
    scanf("%s",find_name);
    p1 = head;
    if(strcmp(find_name,head->name) == 0)
    {   printf("学生 %s 信息已成功删除!\n",head->name);
        p1 = head;
        head = head->next;
        free(p1);}      //释放内存
    else
    {
        while(p1 != NULL)
        {
            p2 = p1->next;
            if(strcmp(find_name,p2->name) == 0)
                {   printf("学生 %s 信息已成功删除!\n",p2->name);
                    p1->next = p2->next;count++;
                    free(p2);break;}        //释放内存
            p1 = p1->next;
        }
        if(count == 0)
            printf("无此学生信息!\n");
    }
}
void delete_num()//按学号查找删除
{
    struct student *p1,*p2;
    int find_num,count = 0;
    printf("请输入需查找的学生学号：");
    scanf("%d",&find_num);
    p1 = head;
    if(find_num == head->num)
    {   printf("学生 %s 信息已成功删除!\n",head->name);
        p1 = head;
        head = head->next;
        free(p1);}      //释放内存
    else
    {
        while(p1 != NULL)
        {
            p2 = p1->next;
            if(find_num == p2->num)
                {   printf("学生 %s 信息已成功删除!\n",p2->name);
                    p1->next = p2->next;count++;
                    free(p2);break;}    //释放内存
            p1 = p1->next;
        }
        if(count == 0)
            printf("无此学生信息!\n");
    }
}
 
void find()//查找学生信息
{
    int choice = -1;
    if(head == NULL)
        printf("无学生信息!\n");
    else
    {
        printf("选择查找方式: 1.按姓名查找 2.按学号查找 0.取消\n");
        scanf("%d",&choice);
        switch(choice)
        {
            case 1: find_name();break;
            case 2: find_num();break;
            case 0: break;
            default: find();break;
        }
    }
}
 
void find_name()//按姓名查找
{
    struct student *p;
    char find_name[20];
    int count = 0;
    printf("请输入需查找的学生姓名：");
    scanf("%s",find_name);
    p = head;
    while(p != NULL)
    {
        if(strcmp(find_name,p->name) == 0)
        {   printf("%s\t%d\t%c\t%.2f\n",p->name,p->num,p->sex,p->score);
            p = p->next;
            count++;}
        else
            p = p->next;
    }
    if(count == 0)
        printf("查无此人！\n");
}
 
void find_num()//按学号查找
{
    struct student *p;
    int find_num,count = 0;
    printf("请输入需查找的学生学号：");
    scanf("%d",&find_num);
    p = head;
    while(p != NULL)
    {
        if(p->num == find_num)
        {   printf("%s\t%d\t%c\t%.2f\n",p->name,p->num,p->sex,p->score);
            p = p->next;
            count++;}
        else
            p = p->next;
    }
    if(count == 0)
        printf("查无此人！\n");
}
 
void display_all()//显示所有学生信息
{
    struct student *p;
    p=head;
    if(p == NULL)
        printf("无学生信息!\n");
    else{
        printf("学生姓名 学号 性别 成绩：\n");
        while(p != NULL)
        {
            printf("%s\t%d\t%c\t%.2f\n",p->name,p->num,p->sex,p->score);
            p=p->next;
        }
    }
}
 
struct student *save(struct student *head)//保存链表数据到文件
{  
    struct student *p; 
    FILE *fp;
    p=head;
 
    if((fp = fopen("student.txt","w")) == NULL)// 易错 \\=\
        printf("文件无法打开!\n");
    else
        fp=fopen("student.txt","w");   
    while(p != NULL)
    {
        fprintf(fp,"%s\t%d\t%c\t%.2f\n",p->name,p->num,p->sex,p->score);
        p=p->next;
    }
    fclose(fp);
    printf("保存成功!\n");
    return head;
}
 
 
struct student *read()//从文件读取链表
{  
    struct student *p1,*p2;
    FILE *fp;  
    int flag = 1;
    fp=fopen("student.txt","r"); 
    printf("学生姓名 学号 性别 成绩\n"); 
    while(!feof(fp)) 
    {
        if(flag == 1)  
        {
            p1=(struct student *)malloc(sizeof(struct student));
            head=p1;
            p2=p1;
            fscanf(fp,"%s %d %c %f\n",p1->name,&p1->num,&p1->sex,&p1->score);
            printf("%s\t%d\t%c\t%.2f\n",p1->name,p1->num,p1->sex,p1->score);
            flag--;
        }
        else
        {
            p1=(struct student *)malloc(sizeof(struct student));
            fscanf(fp,"%s %d %c %f\n",p1->name,&p1->num,&p1->sex,&p1->score);
            printf("%s\t%d\t%c\t%.2f\n",p1->name,p1->num,p1->sex,p1->score);
            p2->next=p1;
            p2=p1;
        }
    }
    p2->next = NULL;
    fclose(fp);
    return head;
}

单向链表网上的文档有很多。。可以参考下面的文档。

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