Structures

C Language / Lesson 11

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Structures

Sample Program #1

Sample Program #2

Download two Sample Programs with structure pointers

/*----- Structures ------*/

/* Following is a structure description */

struct Stud
{ char code[6];
char name[30];
int age;
long fees;
char tel_no[12];
};

/* The previous structure description does not define any variables this means that
there will be later definitions of variables which have the type of the above structure,
for this a tag is required that's why we included the tag Stud in the structure.
Now we can declare variables of the type struct Stud as follows */

struct Stud st[50] , *stp , w ;

/****************************************************
* A structure description with variable declaration *
*****************************************************/
/* ============== with Tag=========== */

struct Stud
{    char code[6];
   char name[30];
   int age;
   long fees;
   char tel_no[12];
} w , a[14];

/* ============= w/o Tag =========== */
struct {
   char code[6];
   char name[30];
   int age;
   long fees;
   char tel_no[12];
} w , a[14];

Structure pointers

Pointers to structures are like all other pointers. They simply point to a structure. For example the definition :

struct Student *sp ;

defines a pointer sp which points to a structure of type struct Student.

Reference to structure members

a member of a structure is denoted as s.member where s is the structure variable.

However, the notation sp.member where sp is a pointer is incorrect because it involve the address of the pointer instead of the address of the structure. To correct this the following notation should be use

(*sp).member

An alternative notation is used for this expression finally because the above notation is not very convenient

sp->member