Sams Teach Yourself C in 21 Days

advanced techniques. In general, you’ll find structures to be useful whenever information

of different variable types should be treated as a group. For example, in a mailing list

database, each entry could be a structure, and each piece of information (name, address,

city, and so on) could be a structure member.

Listing 11.1 pulls together everything that has been covered up to this point. It is not

very practical; however, it illustrates the point of a simple structure.

LISTING11.1 simple.c. Declaring and using a simple structure

1: /* simple.c - Demonstrates the use of a simple structures*/

2:

3: #include <stdio.h>

4:

5: int length, width;

6: long area;

7:

8: struct coord{

9: int x;

10 int y;

11: } myPoint;

12:

13: int main( void )

14: {

15: /* set values into the coordinates */

16: myPoint.x = 12;

17: myPoint.y = 14;

18:

19: printf(“\nThe coordinates are: (%d, %d).”,

20: myPoint.x, myPoint.y);

21:

22: return 0;

23: }

The coordinates are: (12, 14).

This listing defines a simple structure for holding the coordinates of a point. This

is the same structure you’ve seen illustrated earlier in today’s lessons. In line 8

you see that structkeyword is used followed by the tag,coord. The body of the struc-

ture is then defined in lines 9 to 11. This structure is declared with two members,xandy

which are both variables of type int.

In line 11, a variable called myPointis also declared as an instance of the coordstruc-

ture. This declaration could also have been done in a separate line as follows:

struct coord myPoint;

252 Day 11

INPUT/

OUTPUT

ANALYSIS

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