// C program for variable length members in
//structures in GCC
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//A structure of type student
struct student{
    int stu_id;
    int name_len;

    //This is used to store size of flexible
    //character array stud_name[]
    int struct_size;

    //Flexible Array Member(FAM)
    //variable length array must be last
    //member of structure
    char stud_name[];
};

//Memory allocation and initialization of structure
struct student* createStudent(int id,char a[]) {
    //Allocate memory for the struct and the flexible array member
    struct student *s= malloc(sizeof(*s)+sizeof(char)*(strlen(a)+1));//+1 for null terminator

    if(s == NULL){
        perror("Failed to allocate memory");
        exit(EXIT_FAILURE);
    }
    
    s->stu_id=id;
    s->name_len=strlen(a);
    strcpy(s->stud_name,a);//Copy the name into the flexible array member
    
    //Assign size according to the size of stud_name
    s->struct_size=sizeof(*s)+sizeof(char) * (strlen(s->stud_name)+1);

    return s;
}

//Print student details
void printStudent(struct student* s){
    printf("Student_id : %d\n"
           "Stud_Name  : %s\n"
            "Name_Length:%d\n"
            "Allocated_Struct_size: %d\n\n",
             s->stu_id,s->stud_name,s->name_len,
             s->struct_size);

    //Value of Allocated_Struct_size is in bytes here
}

//Driver Code
int main() {
    struct student* s1=createStudent(456,"Shobhit");
    struct student* s2=createStudent(756,"Shubham");
    
    printStudent(s1);
    printStudent(s2);

    //Size of struct student
    printf("Size of Struct student:%lu/n",sizeof(struct student));

    //Size of struct pointer
    printf("Size of Struct pointer:%lu/n",sizeof(s1));

    //Free allocated memory
    free(s1);
    free(s2);

    return 0;
    return 0;
}