我一直在尝试打开程序添加一些值来构造将它们写入文件，然后在重新打开文件时再读取它们。虽然仍然在程序的相同运行中，fread工作（或者可能不会编辑成员），但是当我尝试重新打开时，打印的值是垃圾。我做错了什么，或者做不到那种方式做事。在fwrite之后的文件中它包含“SOH NUL NUL NUL ABCD NUL 1234.000 NUL（x11）”
在prototype.c中有一个加载的函数原型，但我还在main中编写了一个版本（注释掉了同样的函数调用），认为这个问题可能是指针问题但仍然没有运气
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_STUDENTS 100
#define MAX_COURSES 25
#define COURSES_PER_STUDENT 4
#define MAX_GRADES 10
#define STUDENTS_PER_COURSE 20
struct course_record
{
long course_id;
char course_name[5];
char course_number[9];
int number_of_students;
int course_average;
};
struct student_record
{
int student_id;
char first_name[15];
char last_name[15];
int number_of_courses;
int averages[COURSES_PER_STUDENT];
};
struct enrollment_record
{
int id;
struct student_record *student;
struct course_record *course;
int grades[MAX_GRADES];
int average;
struct enrollment_record *next;
};
/****************************************************************************************************************
* *
COURSE STRUCTURE FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
int course_exist(struct course_record *a, char *s, char *t, long n);
int check_number(char *s);
void add_course(struct course_record *a, long *n);
void course_save(struct course_record *a, long *n);
void course_load(struct course_record a, long *n);
/****************************************************************************************************************
* *
STUDENT STRUCTURE FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
/****************************************************************************************************************
* *
ENROLLMENT STRUCTURE FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
/****************************************************************************************************************
* *
MAIN FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
void convert(char *s);`
#include "main.h"
/****************************************************************************************************************
* *
COURSE STRUCTURE FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
//search course function
//check for existing courses
int course_exist(struct course_record *a, char *s, char *t, long n)
{
int i;
for(i = 0; i < n; i++)
{
if(strcmp(a[i].course_name, s) == 0)
{
if(strcmp(a[i].course_number, t) == 0)
return 0;
else
return 1;
}
}
}
//check input format of course number_of_students
int check_number(char *s)
{
int i;
for(i = 0; i < 9; i++)
{
if((isdigit(s[i])) != 0)
return 1;
else if(s[4] != '.')
return 1;
else
return 0;
}
}
//add course function
void add_course(struct course_record *a, long *n)
{
char course_num_temp[9];
char course_name_temp[5];
printf("\nEnter Course Name [ABCD]: ");
scanf("%s", course_name_temp);
printf("\nEnter Course Number [1234.000]:");
scanf("%s", course_num_temp);
a[*n].course_id = *n +1;
strcpy(a[*n].course_name, course_name_temp);
strcpy(a[*n].course_number, course_num_temp);
a[*n].number_of_students = 0;
a[*n].course_average = 0;
}
//save function for courses
void course_save(struct course_record *a, long *n)
{
int i;
FILE *course_file;
course_file = fopen("course.dat", "wb");
for(i = 0; i < *n; i++)
{
fwrite(&(a[i]), sizeof(struct course_record), 1, course_file);
}
fclose(course_file);
}
//load function for courses
void course_load(struct course_record a, long *n)
{
int i;
char temp[40];
FILE *course_file;
course_file = fopen("course.dat", "rb");
if((course_file = fopen("course.dat", "rb")) == '\0')
course_file = fopen("course.dat", "w+b");
fseek(course_file, 0L, SEEK_END);
*n = (ftell(course_file))/((long)sizeof(struct course_record));
printf("\nftell:%ld sizeof:%ld\n", ftell(course_file), (long)sizeof(struct course_record));
printf("\nn:%ld\n", *n);
for(i = 0; i < *n; i++)
{
fread(&temp, sizeof(struct course_record), 1, course_file);
/*printf("%ld %s %s %d %d", a[i].course_id,
a[i].course_name,
a[i].course_number,
a[i].number_of_students,
a[i].course_average);*/
}
fclose(course_file);
}
/******************************************************************************* *********************************
* *
STUDENT STRUCTURE FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
//search student function
//add student function
/****************************************************************************************************************
* *
ENROLLMENT STRUCTURE FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
//search enrollment function
//create enrollment function
/****************************************************************************************************************
* *
MAIN FUNCTION PROTOTYPES
* *
*****************************************************************************************************************/
//check input function for characters
//check input function for integers
//convert characters to uppercase
void convert(char *s)
{
int i, n;
n = strlen(s);
for(i = 0; i < n; i++)
toupper(s[i]);
}
#include "main.h"
int main()
{
//global variable declarations
int i, main_menu;
//variable declarations for course
long course_pos;
struct course_record courses[MAX_COURSES];
FILE *course_file;
//variable declarations for student
int student_pos;
//variable declarations for enrollment
int enroll_pos;
do
{
printf("\nMAIN MAIN\n\n");
printf("1) Add Course\n");
printf("8) Print Courses\n");
printf("11) Save\n");
printf("12) Load\n");
printf("20) Exit\n");
printf("Please make a selection: ");
scanf("%d", &main_menu);
switch(main_menu)
{
case 1:
add_course(courses, &course_pos);
course_pos += 1;
printf("\n%ld\n", course_pos);
break;
case 8:
printf("\nTest\n");
if(course_pos == 0)
printf("No Course Records Exist");
else
{
for(i =0; i < course_pos; i++)
{
printf("%ld %s %s %d %d\n", courses[i].course_id,
courses[i].course_name,
courses[i].course_number,
courses[i].number_of_students,
courses[i].course_average);
}
}
break;
case 11:
course_save(courses, &course_pos);
printf("\nCourses Saved\n");
break;
case 12:
//course_load(*courses, &course_pos);
//printf("\nCourses Loaded\n");
///*
course_file = fopen("course.dat", "rb");
if((course_file = fopen("course.dat", "rb")) == '\0')
course_file = fopen("course.dat", "w+b");
fseek(course_file, 0L, SEEK_END);
course_pos = (ftell(course_file))/((long)sizeof(struct course_record));
printf("\nftell:%ld sizeof:%ld\n", ftell(course_file), (long)sizeof(struct course_record));
printf("\nn:%ld\n", course_pos);
for(i = 0; i < course_pos; i++)
{
fread(&courses[i], sizeof(struct course_record), 1, course_file);
printf("%ld %s %s %d %d\n", courses[i].course_id,
courses[i].course_name,
courses[i].course_number,
courses[i].number_of_students,
courses[i].course_average);
}
fclose(course_file);
//*/
break;
case 20:
printf("\nClosing Program\n");
return 0;
default:
printf("Invalid Input");
break;
}
}while(main_menu !=20);
return 0;
}