Pointers and Structures

struct stud{
    int roll;
    char dept_code[25];
    float cgpa;
} class, *ptr;

struct book{
    char Name[20];
    float price;
    char ISB[30];
}; struct book b, *br;

Allowed

ptr = &class;

br = &b;

Not Allowed

ptr = &b;

br = &class;

Once ptr points to a structure variable, the members can be accessed through a dot operator or an arrow operator.

(*ptr).roll
(*ptr).dept_code
(*ptr).cgpa

ptr->roll
ptr->dept_code
ptr->cgpa

Order of precendence

  1. ()
  2. []
  3. ->
  4. .

Note

  • ptr->roll is equivalent to (*ptr).roll

  • *ptr.roll is invalid

  • *p->x is same as *(p->x)

  • *p[n] is same as *(p+[n])

  • *p->x++ is same as *((p->x)++)

  • ++*p[n] is same as ++(*(p[n]))

  • ++*p->y is same as ++(*(p->y)) and ++(*((*p).y))

structure variables are passed by value just like primitive datatypes(intger, char, float, etc.) The only difference is that the structure name is used instead of the data type name. arrays are generally passed by reference.