Structures

Structure is a collection of one or more variable types. As we know, the elements in an array must be the same data type, and you must refer to the entire array by its name. Each element (called a member) in a structure can be a different data type. Structures have ability to group data of different data types together but work with that data as a whole. Suppose a company has inventory system so item name will be character array, quantity in stock will be integer and retail price will be in double, so to deal with such system we will use structure.  

To define a structure, we must use the struct statement. Struct defines for your program a new data type with more than one member. The format of the struct statement is

struct  {    Member definition;    Member definition;    Member definition;    .    .    . } [one or more structure variables]

Each member definition is a normal variable definition, such as int i; or float sales[20]; or any other valid variable definition, including structure pointers if the structure requires a pointer as a member. At the end of the structure’s definition and before the final semicolon, you can specify one or more structure variables. Here is how you declare the CD structure:

struct cd_collection {     char                 title [ 25 ];     char                 artist [ 20 ];     int                     num_songs;     float                 price;     char                 date_bought [ 8 ]; } cd_collection cd1, cd2, cd3;

 There are five members in above structure: two character arrays, an integer, a floating-point value and a character array. The member names are title, artist, num_songs, price and date_bought. To access member of structure use the following syntax as:

cd1.price, cd2.price etc

Initialization of structure’s member can also be possible when you declare a structure such as:

struct cd_collection {     char                 title [ 25 ];     char                 artist [ 20 ];     int                     num_songs;     float                 price;     char                 date_bought [ 8 ]; } cd_collection cd1 =                                        {                                             “Red Moon Men”,                                             “Sam and the sneeds”,                                               12,                                                200.50,                                               11/10/14”                                        };

To store data of 100 books one must require to use 100 different structure variables from book1 to book100, which is not very convenient. A better approach would be to use an array of structure.