• An array is used to store and process a group of homogeneous elements. But, to store and process eleents that are not homogeneous, the knowledge of the structure is required. Structures help in packing the disimilar data items under a single name.
• A structure is a meaningful collection of data items of different type. But it collects all elements under a unique name. A structure allows the programmer to create and manipulate a set of different types of data items.
• The keyword struct.

• Each and every structure must be defined and declared before it appear in a C program.
• The body of the structure is terminated by a semicolon.

struct employee
{
int emp_code;
char name[20];
float salary;
};

• The general form of declaring structure variables is :

structure_type varlist;

• A structure within another structure is called an embedded structure.
• A structure may completely be defined within the other structure.
• There may be separate strucutres.The embedded structure is declared first and the other structure is declared next.




• Like initialization of array elements, structure members can be initialized.
• Each member of a structure is accessed with the dot operator.
• The dot operator has the highest priority than any other operator of C, and it’s associativity is from left to right.

• Whenever the same structure is to be applied to a group of people, items or applications we will have to use an array of structures.

• typedef(for type definition) statement – enables the programmer to define an alternate term to the basic data types.

Syntax – typedef old_data_type new_data_type;

• A union is a collection of heterogeneous data elements. They are similar to structures.
• However, there is a difference in the way the structure members and union members are stored. Each member within a structure is asigned its own memory location. But the union members, all share a common memory location. Thus, unions are used to save memory.
• An inividual member of a union can be accessed using the dot operator or ->(arrow) operator.

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Related posts:

1. Arrays
2. Pointers
3. Constants and Variables
4. Strings(Character Arays)
5. Loop Control Structures(Decision Making & Looping)