How to get struct from a file in C - c

Question

I am new to programming and would like some help in for File in C.
This is my code
#include <stdio.h>
#include <string.h>
void read_file();
void write_fil();
void add();
void display();
void search();
#define NAME_CHRS 30
struct employee_rec
{ char name[NAME_CHRS];
int dependents;
float pay_rate;
};
struct employee_rec employee;
struct employee_rec emp_array[];
FILE *employ;
int count=-1;
void read_file(void)
{
int idx;
employ = fopen("EMPLOYEE.DAT", "a+");//i add
//for (idx=0; idx <= count; idx++)
fread(&emp_array[idx], sizeof emp_array[idx], 1, employ);
fclose(employ);
}
void write_file()
{
int x;
employ = fopen("EMPLOYEE.DAT", "a+");
for (x=0; x <= count; x++)
fwrite(&emp_array[x], sizeof emp_array[x], 1, employ);
fclose(employ);
}
void add()
{
count+=1;
printf("Enter name: ");
scanf("%s", emp_array[count].name);
printf("Pay rate, other dependents: ");
scanf("%f %i", &emp_array[count].pay_rate, &emp_array[count].dependents);
}
void display()
{
int idx;
read_file();
printf("Name\t\tPay Rate\tDependents\n");
printf("----\t\t--------\t----------\n");
for (idx=0; idx <= count; idx++)
{
printf("%-10s\t%-8g\t%-8d\n", emp_array[idx].name, emp_array[idx].pay_rate, emp_array[idx].dependents);
}
}
void search()
{
char target[20];
int idx, found=0;
printf("Enter a name to search: ");
scanf("%s", target);
for (idx=0; idx <= count; idx++){
if(strcmp(emp_array[idx].name, target) == 0)
{
found = 1;
break;
}
}
if(found == 1)
{
printf("Name: %s\n", emp_array[idx].name);
printf("Pay rate: %g\n", emp_array[idx].pay_rate);
printf("Dependents: %d\n", emp_array[idx].dependents);
}
else
printf("Not found!\n");
}
int main(void)
{
int i;
//for (i=0; i < 3; i++)
// add();
// write_file();
display();
search();
return 0;
}
The original program would ask the user to key in data and then display it for the user.
So when another user runs the program and has the file it doesnt need to add more data but just read from the file
I have commented the for loop, display and search in my main because i just want to retrieve the data from my file.
Im not sure what to do with
fread(&emp_array[idx], sizeof emp_array[idx], 1, employ);
fclose(employ);
Since right now im using the counter from the insert to get the size, it will say size is 0 as the current run did not enter the data into the file (file already has data).
Is there any other way I can get all my data from the file without inserting it in the same run?
EDIT: So as some of the comments have mentioned the size of emp_arry is empty. I would like to get the size from a file. Since the file as a array inside which i want to transfer the data to emp_array.

Answer 1

One simple solution is to design a file header which includes the number of data in this file. Then, you can first read file header to get the number and then dynamically allocate memory to read data from file.