Structure and Pointer

   To store address of a structure type variable, we can define a structure type pointer variable as normal way. Let us consider an structure book that has members name, page and price. It can be declared as

           struct book

                 {

                    char name[10];

                   int page;

                   float price;

                    };

Then, we can define structure variable and pointer variable of structure type. This can be done as

         struct book b, *bptr;

       Here,

                     b is the structure variable and bptr is pointer variable which points address of structure variable. It can be done as

                    bptr=&b;

        Here, the base address of b can assigned to bptr pointer.

An individual structure member can be accessed in terms of its corresponding pointer variable by writing

            ptr_variable->member

  Here, -> is called arrow operator and there must be pointer to the structure on the left side of  this operator.

Example:

     Create a structure named book which has name, pages and price as member variables. Read name of book, its page number and price. Finally display these members’ value. Use pointer to structure instead of structure itself to access member variables.

  void main()

{

    struct book

         {

         char name[20];

         int pages;

         float price;

          };

  struct book b={"Let us C",230,456.50},*ptr; // structure initialization

  ptr=&b;

  clrscr();

  printf("\nName=%s\tPages=%d\tPrice=%f",ptr->name,ptr->pages,ptr->price);

                       /* same as b.name, b.pages and b.price */

  getch();

}

Here, ptr->name refers the content at address pointed by ptr variable.