How to read, modify structs from a non-text file? - c

Question

I want to save some struct into a file and read all of them or modify them. I tried like this, but this way I got only the last saved structs, and I don't know how to get all of them, or how to modify them later in the file.
I don't get any error just the last saved structs, but in the file I see all of them if I open with a text editor.
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#define MAX_STRING_LEN 80
#define PHONE_NUMBER 15
struct order {
time_t systime;
char name[MAX_STRING_LEN];
char email[MAX_STRING_LEN];
int phonenumber;
int size;
};
//functions
void saveToFiles(struct order *current);
void dbList(struct order *current);
//save into file
void saveToFiles(struct order *current) {
FILE * file=fopen("db.txt", "a");
if(file != NULL) {
fwrite(current, sizeof(struct order), 1, file);
// fwrite("\n", sizeof("\n"), 1, file); //If I broke the line then all of the reading get some numbers, without any meaning
fclose(file);
}
}
//list the db
void dbList(struct order *current) {
int option;
printf("list: \n 1 - ful list\n 2 - just names\n 3 - just size\n 0 - exit");
scanf(" %i", &option);
if(option == 0) {
exit(1);
}
if(option == 1) {
//loadList(1);
struct order *obj=malloc(sizeof(struct order));
FILE * file = fopen("db.txt","rb");
fseek(file, 0, SEEK_SET); //I tried to put the file read at the begining of the file
while(fread(obj, sizeof(struct order), 1, file)) {
printf("LOG: op1\n");
fread(obj, sizeof(struct order), 1, file);
printf("%s/%s/%d/%d\n", obj->name, obj->email, obj->phonenumber, obj->size);
}
if(feof(file)) {
printf("\n--END--\n");
}
else {
printf("Some error...");
}
}
}
//***
int main(k)
{
struct order current; //struct init
// current = malloc(sizof(*current));
int option = 1;
while(option != 0) {
printf(" " "\x1B[34m");
printf("0 exit \n 1 new \n 2 list \n \n " "\x1B[0m");
scanf(" %i", &option);
if(option == 1) {
getNewOrder(&current);
}
if(option == 2) {
dbList(&current);
}
}
return 0;
}

Answer 1

For write file, pls check if fseek() to SEEK_END and then do fwrite can help.