This document discusses derived data types in C including structures, unions, and enumerations. Structures allow grouping different data types together under one name. Unions share the same memory location for different variable types. Enumerations define a set of named integer constants.

1. Derived Data Types
What you’ll learn:
o What are derived data types
o Structures
o Unions
o Enumerations

2. What are Derived Data types ?
 These are composed of more than one type of data.
 We have already covered array and strings.
 More derived data types:
 Structures
 Unions
 Enumerations

3. Structure
 Structure can contain more than one type of data.
 Syntax:
struct tag_name{
Data_type_1 variable_name;
…..
Data_type_n variable_name;
}
Struct tag_name variable_list; (Note: Variable list is of type struct)

4. Union
 Special data type that enables us to store different types of data in the same memory
location, i.e. memory is shared between these variables.
 Only one member occupies memory at a given time.
 Efficient way of using same memory location.
 Prevents memory fragmentation.

5. Enumeration
 Consists of a set of named integer constants.
 Syntax:
enum tag_name{
……enum-list------
}