1. Chapter 12 Enumerated, Structure, and Union Types Objectives
❏ To introduce the structure, union, and enumerated types
❏ To use the type definition statement in programs
❏ To use enumerated types, including anonymous types.
❏ To create and use structures in programs
❏ To be able to use unions in programs
❏ To understand the software engineering concept of coupling and to be able to evaluate coupling between functions.
Computer Science: A Structured Programming Approach Using C

2. FIGURE Derived Types
Computer Science: A Structured Programming Approach Using C

3. 12-1 The Type Definition (typedef)
Before discussing the derived types, let’s discuss a C declaration that applies to all of them—the type definition. A type definition, typedef, gives a name to a data type by creating a new type that can then be used anywhere a type is permitted.
Computer Science: A Structured Programming Approach Using C

4. FIGURE 12-2 Type-definition Format
Computer Science: A Structured Programming Approach Using C

5. Topics discussed in this section:
Enumerated Types
The enumerated type is a user-defined type based on the standard integer type. In an enumerated type, each integer value is given an identifier called an enumeration constant.
Topics discussed in this section:
Declaring an Enumerated Type
Operations on Enumerated Types
Enumeration Type Conversion
Initializing Enumerated Constants
Anonymous Enumeration: Constants
Input/Output Operations
Computer Science: A Structured Programming Approach Using C

6. Print Cable TV Stations
PROGRAM 12-1
Print Cable TV Stations
Computer Science: A Structured Programming Approach Using C

7. Print Cable TV Stations
PROGRAM 12-1
Print Cable TV Stations
Computer Science: A Structured Programming Approach Using C

8. Note Don’t be confused about strings and enumerated types.
“Jan” is a string made of three characters; JAN
as defined in the previous code example, is an
enumerated type (identifier) which
has the integer value 1.
Computer Science: A Structured Programming Approach Using C

9. Topics discussed in this section:
Structure
A structure is a collection of related elements, possibly of different types, having a single name.
Topics discussed in this section:
Structure Type Declaration
Initialization
Accessing Structures
Operations on Structures
Complex Structures
Structures and Functions
Computer Science: A Structured Programming Approach Using C

10. FIGURE 12-3 Structure Examples
Computer Science: A Structured Programming Approach Using C

11. should be logically related.
Note
Elements in a structure can be of the same or different types. However, all elements in the structure
should be logically related.
Computer Science: A Structured Programming Approach Using C

12. FIGURE 12-4 Tagged Structure Format
Computer Science: A Structured Programming Approach Using C

13. FIGURE 12-5 Structure Declaration with typedef
Computer Science: A Structured Programming Approach Using C

14. FIGURE 12-6 Structure Declaration Format and Example
Computer Science: A Structured Programming Approach Using C

15. FIGURE 12-7 Initializing Structures
Computer Science: A Structured Programming Approach Using C

16. FIGURE 12-8 Structure Direct Selection Operator
Computer Science: A Structured Programming Approach Using C

17. PROGRAM 12-2 Multiply Fractions
Computer Science: A Structured Programming Approach Using C

18. PROGRAM 12-2 Multiply Fractions
Computer Science: A Structured Programming Approach Using C

19. FIGURE 12-9 Copying a Structure
Computer Science: A Structured Programming Approach Using C

20. FIGURE 12-10 Pointers to Structures
Computer Science: A Structured Programming Approach Using C

21. (*pointerName).fieldName « pointerName->fieldName.
Note
(*pointerName).fieldName « pointerName->fieldName.
Computer Science: A Structured Programming Approach Using C

22. FIGURE 12-11 Interpretation of Invalid Pointer Use
Computer Science: A Structured Programming Approach Using C

23. FIGURE 12-12 Indirect Selection Operator
Computer Science: A Structured Programming Approach Using C

24. Clock Simulation with Pointers
PROGRAM 12-3
Clock Simulation with Pointers
Computer Science: A Structured Programming Approach Using C

25. Clock Simulation with Pointers
PROGRAM 12-3
Clock Simulation with Pointers
Computer Science: A Structured Programming Approach Using C

26. Clock Simulation with Pointers
PROGRAM 12-3
Clock Simulation with Pointers
Computer Science: A Structured Programming Approach Using C

27. Clock Simulation with Pointers
PROGRAM 12-3
Clock Simulation with Pointers
Computer Science: A Structured Programming Approach Using C

28. FIGURE 12-13 Nested Structure
Computer Science: A Structured Programming Approach Using C

29. FIGURE 12-14 Arrays in Structures
Computer Science: A Structured Programming Approach Using C

30. FIGURE 12-15 Pointers in Structures
Computer Science: A Structured Programming Approach Using C

31. FIGURE 12-16 Array of Structures
Computer Science: A Structured Programming Approach Using C

32. Sort Array of Student Structures
PROGRAM 12-4
Sort Array of Student Structures
Computer Science: A Structured Programming Approach Using C

33. Sort Array of Student Structures
PROGRAM 12-4
Sort Array of Student Structures
Computer Science: A Structured Programming Approach Using C

34. Sort Array of Student Structures
PROGRAM 12-4
Sort Array of Student Structures
Computer Science: A Structured Programming Approach Using C

35. Sort Array of Student Structures
PROGRAM 12-4
Sort Array of Student Structures
Computer Science: A Structured Programming Approach Using C

36. Sort Array of Student Structures
PROGRAM 12-4
Sort Array of Student Structures
Computer Science: A Structured Programming Approach Using C

37. Sort Array of Student Structures
PROGRAM 12-4
Sort Array of Student Structures
Computer Science: A Structured Programming Approach Using C

38. FIGURE 12-17 Passing Structure Members to Functions
Computer Science: A Structured Programming Approach Using C

39. FIGURE 12-18 Passing and returning structures
Computer Science: A Structured Programming Approach Using C

40. Passing and Returning Structures
PROGRAM 12-5
Passing and Returning Structures
Computer Science: A Structured Programming Approach Using C

41. Passing and Returning Structures
PROGRAM 12-5
Passing and Returning Structures
Computer Science: A Structured Programming Approach Using C

42. Passing and Returning Structures
PROGRAM 12-5
Passing and Returning Structures
Computer Science: A Structured Programming Approach Using C

43. Passing and Returning Structures
PROGRAM 12-5
Passing and Returning Structures
Computer Science: A Structured Programming Approach Using C

44. Passing and Returning Structures
PROGRAM 12-5
Passing and Returning Structures
Computer Science: A Structured Programming Approach Using C

45. FIGURE 12-19 Passing Structures Through Pointers
Computer Science: A Structured Programming Approach Using C

46. Passing Structures through Pointers
PROGRAM 12-6
Passing Structures through Pointers
Computer Science: A Structured Programming Approach Using C

47. Passing Structures through Pointers
PROGRAM 12-6
Passing Structures through Pointers
Computer Science: A Structured Programming Approach Using C

48. Passing Structures through Pointers
PROGRAM 12-6
Passing Structures through Pointers
Computer Science: A Structured Programming Approach Using C

49. Passing Structures through Pointers
PROGRAM 12-6
Passing Structures through Pointers
Computer Science: A Structured Programming Approach Using C