![Example of Union
The union of Employee is declared as
union employee
{
int emp_id;
char name[20];
float salary;
char address[50];
int dept_no;
int age;
};](https://image.slidesharecdn.com/union-160911194119/85/Union-In-language-C-4-320.jpg)
Union In language C
- 1. RAVI SHANKAR B.TECH CSE 2ND YEAR 4915123 UNION
- 2. Union Data Type A union is a user defined data type like structure. The union groups logically related variables into a single unit. The union data type allocate the space equal to space need to hold the largest data member of union. The union allows different types of variable to share same space in memory. There is no other difference between structure and union than internal difference. The method to declare, use and access the union is same as structure.
- 3. Defining of Union A union has to defined, before it can used. The syntax of defining a structure is union <union_name> { <data_type> <variable_name>; <data_type> <variable_name>; …….. <data_type> <variable_name>; };
- 4. Example of Union The union of Employee is declared as union employee { int emp_id; char name[20]; float salary; char address[50]; int dept_no; int age; };
- 5. Memory Space Allocation 8000 emp_id, dept_no, age 8002 salary 8004 name 8022 address 8050 employee
- 6. Difference between Structures & Union 1)The memory occupied by structure variable is the sum of sizes of all the members but memory occupied by union variable is equal to space hold by the largest data member of a union. 2)In the structure all the members are accessed at any point of time but in union only one of union member can be accessed at any given time.
- 7. Application of Structures Structure is used in database management to maintain data about books in library, items in store, employees in an organization, financial accounting transaction in company. Beside that other application are 1)Changing the size of cursor. 2)Clearing the contents of screen. 3)Drawing any graphics shape on screen. 4)Receiving the key from the keyboard.
- 8. Summary • The member of structure variable is accessed by pointer variable with arrow operator (). • The structure variable can be passed to a function as a parameter. • The function can return a variable of structure type. • A union is like structure that group logically related variables into a single unit. The union allocate the space equal to space need to hold the largest data member of union. • Structure used in database management and many more applications.
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