结构体数组的写入读取问题,C\C++交流,技术交流,鱼C论坛

GALI 发表于 2018-6-19 21:44:36

结构体数组的写入读取问题

为什么读取失败。{:10_277:}

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#define MAXSTU 200 /*添加学生的最大人数*/
struct student
{
long num;
char name;
float math, English, C, physics;
float sum;
float average;
}msg;

typedef struct student * pst; /* 定义指针类型*/
int count = 0;

int menu_select() //选择功能菜单；
{
int i;
printf(" 1.添加学生信息\n");
printf(" 2.显示学生信息\n");
printf(" 3.保存学生信息\n");
printf(" 4.读取学生信息\n");
printf(" 5.退出程序 \n");
do
{
printf("请输入功能序号: ");
scanf("%d", &i);
}while(i<=0||i>7);
return i;
}

void add_student(pst p); //添加学生成绩
void dis_student(pst p); //显示学生成绩
void save_student(); //保存学生信息
void read_student(); //读取学生信息

int main()
{
pst p = msg; /* 定义指针 */

while(1)
{
system("cls");
switch(menu_select())
{
case 1:
{
add_student(p);
break;
}
case 2:
{
dis_student(p);
break;
}
case 3:
{
save_student();
break;
}
case 4:
{
read_student();
break;
}
case 5:
exit(0);
}
}
system("pause");
return 0;
}

void add_student(pst p)
{
float temp;
printf("\t(学号为零输入结束)\n");
do
{
printf("请输入学号：");
scanf("%ld", &(p+count)->num);
if ((p+count)->num == 0)    /* 输入学号为零，退出循环*/
break;
printf("请输入学生的名字: ");
scanf("%s",&(p+count)->name);
printf("请输入高数的成绩: ");
scanf("%f", &temp);
(p+count)->math = temp;
printf("请输入英语的成绩: ");
scanf("%f", &temp);
(p+count)->English = temp;
printf("请输入C语言的成绩: ");
scanf("%f", &temp);
(p+count)->C = temp;
printf("请输入物理的成绩: ");
scanf("%f", &temp);
(p+count)->physics = temp;

(p+count)->sum = ((p+count)->math + (p+count)->English +
   (p+count)->C + (p+count)->physics);
(p+count)->average = ((p+count)->sum) / 4;

count++;
printf("输入完成,请按任意键继续.....\n");
getch();
} while (1);
}

void dis_student(pst p) //显示学生成绩
{
int i;

if(count)
{
printf("===========================================================================\n");
printf("\t学号\t姓名\t高数\t英语\tC语言\t物理\t总分\t平均分\n");
for (i = 0; i < count; i++)
{
printf(" %d\t%ld\t%s\t%0.1f\t%0.1f\t%0.1f\t%0.1f\t%0.1f\t%0.1f\n\n", (p+i)->num, (p+i)->name,
(p+i)->math, (p+i)->English, (p+i)->C, (p+i)->physics, (p+i)->sum, (p+i)->average);
}
}
else
printf("当前无学生信息.......\n");
system("pause");
}

void save_student() // 保存学生成绩
{
int i;
printf("\n\t\t\t********保存学生信息********\t\t\t\n");
FILE *fp=fopen("student.txt","wb");
for(i=0;i<count;i++)
{
if(fwrite(&msg,sizeof(struct student),1,fp)!=1)
printf("\t    error \n");
}
fclose(fp);
system("pause");
}

void read_student() //读取学生信息
{
int i,f;
FILE *fp;
printf("\n\t\t\t*******读取学生信息*******\t\t\t\n");
if((fp = fopen("student.txt","rb")) == NULL)
{
printf("Can not open file\n");
if((fp=fopen("student.txt","w"))==NULL)
printf("文件无法打开");
}
fseek(fp,0,SEEK_END);
if(ftell(fp)>0)
{
rewind(fp);
for(i=0;i<count;i++)
{
f=fread(&msg,sizeof(struct student),1,fp);
}
}
if(f!=1)
{
printf("文件导入失败.");
}
else
printf("文件导入成功");

system("pause");
fclose(fp);
}

ba21 发表于 2018-6-19 22:11:42

for(i=0;i<count;i++)
            {
                     f=fread(&msg,sizeof(struct student),1,fp);
            }

count 的大小你如何确定？

GALI 发表于 2018-6-19 23:13:22

ba21 发表于 2018-6-19 22:11
for(i=0;i

噢噢，看到了，感谢！
但是从文本读进结构体数组，我还是不太懂怎么写，可以稍微讲一下吗{:10_277:}

ba21 发表于 2018-6-20 09:30:02

GALI 发表于 2018-6-19 23:13
噢噢，看到了，感谢！
但是从文本读进结构体数组，我还是不太懂怎么写，可以稍微讲一下吗
参考：
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

#define MAXSTU 200 /*添加学生的最大人数*/
struct student
{
   long num;
   char name;
   float math, English, C, physics;
   float sum;
   float average;
}msg;

typedef struct student * pst; /* 定义指针类型*/
int count = 0;

int menu_select() //选择功能菜单；
{
   int i;
   printf(" 1.添加学生信息\n");
   printf(" 2.显示学生信息\n");
   printf(" 3.保存学生信息\n");
   printf(" 4.读取学生信息\n");
   printf(" 5.退出程序 \n");
   do
   {
            printf("请输入功能序号: ");
            scanf("%d", &i);
   }while(i<=0||i>7);
   return i;
}

void add_student(pst p); //添加学生成绩
void dis_student(pst p); //显示学生成绩
void save_student(); //保存学生信息
void read_student(); //读取学生信息

int main()
{
   pst p = msg; /* 定义指针 */

   while(1)
   {
            system("cls");
            switch(menu_select())
            {
                     case 1:
                           {
                                    add_student(p);
                                    break;
                           }
                     case 2:
                           {
                                    dis_student(p);
                                    break;
                           }
                     case 3:
                           {
                                    save_student();
                                    break;
                           }
                     case 4:
                           {
                                    read_student();
                                    break;
                           }
                     case 5:
                           exit(0);
            }
   }
   system("pause");
   return 0;
}

void add_student(pst p)
{
   float temp;
   printf("\t(学号为零输入结束)\n");
   do
   {
            printf("请输入学号：");
            scanf("%ld", &(p+count)->num);
            if ((p+count)->num == 0)    /* 输入学号为零，退出循环*/
                     break;
            printf("请输入学生的名字: ");
            scanf("%s",&(p+count)->name);
            printf("请输入高数的成绩: ");
            scanf("%f", &temp);
            (p+count)->math = temp;
            printf("请输入英语的成绩: ");
            scanf("%f", &temp);
            (p+count)->English = temp;
            printf("请输入C语言的成绩: ");
            scanf("%f", &temp);
            (p+count)->C = temp;
            printf("请输入物理的成绩: ");
            scanf("%f", &temp);
            (p+count)->physics = temp;

            (p+count)->sum = ((p+count)->math + (p+count)->English +
                                                      (p+count)->C + (p+count)->physics);
            (p+count)->average = ((p+count)->sum) / 4;

            count++;
            printf("输入完成,请按任意键继续.....\n");
            getch();
   } while (1);
}

void dis_student(pst p) //显示学生成绩
{
int i;

   if(count)
   {
            printf("===========================================================================\n");
            printf("\t学号\t姓名\t高数\t英语\tC语言\t物理\t总分\t平均分\n");
            for (i = 0; i < count; i++)
            {
                     printf(" %d\t%ld\t%s\t%0.1f\t%0.1f\t%0.1f\t%0.1f\t%0.1f\t%0.1f\n\n", (p+i)->num, (p+i)->name,
                                             (p+i)->math, (p+i)->English, (p+i)->C, (p+i)->physics, (p+i)->sum, (p+i)->average);
            }
   }
   else
            printf("当前无学生信息.......\n");
   system("pause");
}

void save_student() // 保存学生成绩
{
   int i;
FILE *fp=fopen("student.txt","wb");
   printf("\n\t\t\t********保存学生信息********\t\t\t\n");

   for(i=0;i<count;i++)
   {
            if(fwrite(&msg,sizeof(struct student),1,fp)!=1)
                     printf("\t    error \n");
   }
   fclose(fp);
   system("pause");
}

void read_student() //读取学生信息
{
   FILE *fp;
count=0;
   printf("\n\t\t\t*******读取学生信息*******\t\t\t\n");
   if((fp = fopen("student.txt","rb")) == NULL)
   {
            printf("Can not open file\n");
            if((fp=fopen("student.txt","w"))==NULL)
                     printf("文件无法打开");
   }
   fseek(fp,0,SEEK_END);
   if(ftell(fp)>0)
   {
            rewind(fp);
fread(&msg,sizeof(struct student),1,fp);
            while (!feof(fp))
            {
                     fread(&msg[++count],sizeof(struct student),1,fp);
            }
   }
   if(count)
   {
printf("文件导入成功");

   }
   else
         printf("文件导入失败.");

   system("pause");
   fclose(fp);
}

GALI 发表于 2018-6-20 13:10:57

ba21 发表于 2018-6-20 09:30
参考：

万分感谢！！

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结构体数组的写入读取问题