Array of pointers to a struct with pointers in that struct

Question

The part that is bothering me is the last for loop which I used just to test whether the data is entered correctly and that it is printed using printf properly. The three access methods used to print the data which I entered aren't quite clear to me.

In access method #1 I managed to print data properly using only one arrow operator to access name. The part I can't wrap my head around is why am I able to access the data without an error? I only used index to access each production_plant_employees structure. I know the brackets do the dereferencing, but I still don't understand what's happening there. I tried writing that part like this : *(production_plant_employees + i), but it didn't work.

Access method #2 is fully clear to me.

Now the access method #3, that's the one I assumed would work, but it refuses to. When written, IDE shows no errors, but when I run the program, it stops.

I am supposed to first access data in first pointer (which is production_plant_employees), and then then access data in second pointer (which is pointer basic_info which is in struct employee), and then, when I've gone through the 2 pointers, access the very data I am after (name, age, etc...), right?

Also, could you please show me any other possible ways of accessing the data I'm after?

typedef struct basicdata{
 char name[15];
 char last_name[15];
 char gender[2];
 int age;
 char birthplace[15];
 char address[15];
} BASICDATA;
typedef struct job_info {
 int employment_year;
 char job_position[20];
 char employee_pay_grade[10];
 int employee_grade;
} JOB_INFO;
typedef struct employee{
 BASICDATA *basic_info;
 JOB_INFO *job_info;
} EMPLOYEE;
int main () {
 int i;
 int choice = 0;
 EMPLOYEE *production_plant_employees;
 printf("Enter number of employees : \n");
 scanf("%d", &choice);
 production_plant_employees = (EMPLOYEE*)calloc(choice, sizeof(EMPLOYEE));
 if (production_plant_employees == NULL) {
 printf("An error occured during memory allocation\n");
 }
 for(i = 0; i < choice; ++i) {
 production_plant_employees[i].basic_info = (BASICDATA*)calloc(choice, sizeof(BASICDATA));
 if(production_plant_employees[i].basic_info == NULL) {
 printf("An error occured during memory allocation\n");
 }
 production_plant_employees[i].job_info = (JOB_INFO*)calloc(choice, sizeof(JOB_INFO));
 if(production_plant_employees[i].job_info == NULL) {
 printf("An error occured during memory allocation\n");
 }
 printf("production_plant_employees[%d].basic_info = %d\t%x\n", i, production_plant_employees[i].basic_info, production_plant_employees[i].basic_info);
 printf("production_plant_employees[%d].job_info = %d\t%x\n", i, production_plant_employees[i].job_info, production_plant_employees[i].job_info);
 }
 for(i = 0; i < choice; ++i) {
 fflush(stdin);
 printf("Enter name : \n");
 fgets(production_plant_employees[i].basic_info->name, 15, stdin);
 printf("Name of %d. employee : %s", i, production_plant_employees[i].basic_info->name) //access method#1
 printf("Name of %d. employee : %s", i, (production_plant_employees + i)->basic_info->name); //access method #2
 printf("Name of %d. employee : %s", i, *(*(production_plant_employees +i)).basic_info->name); //access method #3 ---> why isn't this working?
 printf("\n\n");
 }
 return 0;
}

• yano: when printing pointers, use the %p format specifier and cast them to void*: printf("production_plant_employees[%d].basic_info = %p", i, (void*)production_plant_employees[i].basic_info); Also, fflush(stdin); is undefined behavior.
• John Bollinger: Look up the relative precedence and associativity of the operators involved. In particular, look at the precedence of the dereferencing operator (*) relative to the member-selection (.) and indirect member selection (->) operators.

Answer 1

The right way to do it is (for access method 3):

printf("Name of %d. employee : %s", i, (*(*(production_plant_employees +i)).basic_info).name);

First we start by dereferencing pointer production_plant_employees +i, now, we access member basic_info which is also a pointer & needs to get dereferenced using the second * to access local member name.

ptr1 = production_plant_employees +i
ptr2 = (*ptr1).basic_info
data = (*ptr2).name

And thus (substituting ptr2 in data:

data = (*(*ptr1).basic_info).name

& finally by substituting ptr1 :

data = (*(*(production_plant_employees +i)).basic_info).name

• Apollo: Oh boy... Thanks for answering so quickly, it works :D Btw. I was so close couple of minutes ago. Thanks a lot!