Hello, I've been having problems with my program. I really don't get files that much. This is my code:


#define max 3

typedef struct
	 char FName[24];
	 char LName[16];
	 char MI;

typedef struct
	 unsigned long ID;
	 name n;
	 char course[8];
	 int level;

typedef struct
	 profile *p;
	 int last;
}student_record, *srptr;

void initialize(srptr *s);
void insert(srptr *s);
void display(srptr s);
void write_file(srptr s);
void read_file(srptr *s);

void initialize(srptr *s)
	 *s = (srptr) malloc(sizeof(student_record));
	 (*s)->p = (profile *) malloc(sizeof(profile) * max);
	 (*s)->last = -1;

void insert(srptr *s)
	 strcpy((*s)->p[++(*s)->last].n.FName, "Bradd");
	 strcpy((*s)->p[(*s)->last].n.LName, "Pitt");
	 (*s)->p[(*s)->last].n.MI = 'P';
	 (*s)->p[(*s)->last].ID = 7000000;
	 strcpy((*s)->p[(*s)->last].course, "BSIT");
	 (*s)->p[(*s)->last].level = 3;

	 strcpy((*s)->p[++(*s)->last].n.FName, "Angelina");
	 strcpy((*s)->p[(*s)->last].n.LName, "Jolie");
	 (*s)->p[(*s)->last].n.MI = 'M';
	 (*s)->p[(*s)->last].ID = 7111111;
	 strcpy((*s)->p[(*s)->last].course, "BSICT");
	 (*s)->p[(*s)->last].level = 1;

	 strcpy((*s)->p[++(*s)->last].n.FName, "Tom");
	 strcpy((*s)->p[(*s)->last].n.LName, "Cruise");
	 (*s)->p[(*s)->last].n.MI = 'A';
	 (*s)->p[(*s)->last].ID = 7222222;
	 strcpy((*s)->p[(*s)->last].course, "ACTMT");
	 (*s)->p[(*s)->last].level = 2;

void display(srptr s)
	 int ctr;

	 for(ctr = 0; ctr < max; ctr++)
		  printf("%d)\n", ctr + 1);
		  printf("%s %c. %s\n", s->p[ctr].n.FName, s->p[ctr].n.MI, s->p[ctr].n.LName);
		  printf("%li\n", s->p[ctr].ID);
		  printf("%s %d\n", s->p[ctr].course, s->p[ctr].level);

void write_file(srptr s)
	 FILE *fp;
	 int ctr;

	 if((fp = fopen("test.dat", "wb")) == NULL)
		  printf("Cannot open file\n");

	 for(ctr = 0; ctr <= s->last; ctr++)
		  fwrite(&s->p[ctr].ID, sizeof(long), 1, fp);
		  fwrite(&s->p[ctr].n.FName, sizeof(char), strlen(s->p[ctr].n.FName), fp);
		  fwrite(&s->p[ctr].n.LName, sizeof(char), strlen(s->p[ctr].n.LName), fp);
		  fwrite(&s->p[ctr].n.MI, sizeof(char), 1, fp);
		  fwrite(&s->p[ctr].course, sizeof(char), strlen(s->p[ctr].course), fp);
		  fwrite(&s->p[ctr].level, sizeof(int), 1, fp);
	 printf("File Saved\n");

void read_file(srptr *s)
	 FILE *fp;
	 int ctr;

	 if((fp = fopen("test.dat", "rb")) == 0)
		  printf("File is empty\n");

	 for(ctr = 0; ctr < max; ctr++)
		  fread(&(*s)->p[ctr].ID, sizeof(long), 1, fp);
		  fread(&(*s)->p[ctr].n.FName, sizeof(char), strlen((*s)->p[ctr].n.FName), fp);
		  fread(&(*s)->p[ctr].n.LName, sizeof(char), strlen((*s)->p[ctr].n.LName), fp);
		  fread(&(*s)->p[ctr].n.MI, sizeof(char), 1, fp);
		  fread(&(*s)->p[ctr].course, sizeof(char), strlen((*s)->p[ctr].course), fp);
		  fread(&(*s)->p[ctr].level, sizeof(int), 1, fp);
	 printf("File Loaded\n");

void main()
	 srptr s;





I run the program two times. First,
It will write the data that are in function insert to file "test.dat". The read_file function call doesn't exist yet.
The second time I run the program, the function call insert and write_file are deleted and function call read_file is created.

I've been getting garbage value and I can't figure out why. Please help.

  1. Do not use void main().
  2. Always try to free the memory which is allocated.
  3. When you run the program for the second time by deleting insert and write_file, then the strlen function will be garbage. i.e, strlen((*s)->p, [ctr].n.FName), , strlen((*s)->p[ctr].n.LName), and strlen((*s)->p[ctr].course), in the read_file, function are garbage, hence you get garbage result when you display.
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