CPS120: Introduction to Computer Science

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CPS120 Introduction to Computer Science

• Structures

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Using enum

• enum allows you to create your own simple data
  types for special purposes
• Create a type
• Give it a name
• Specify values that are acceptable
• enum sizes small, medium, large, jumbo
• The compiler assigns an integer to each enum item

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Composite Data Types

• Records
• A record is a named heterogeneous collection of
  items in which individual items are accessed by
  name
• The elements in the collection can be of various
  types

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Structures

• Structures group variables together in order to
  make one's programming task more efficient.
• Any combination of variables can be combined into
  one structure.
• This is a useful and efficient way to store data.
  
• struct Student
• string socSecNum
• string lastName
• string firstName
• int pointsEarned
• double gpa

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Using Structures

• Each of the different variables are called
  members of the structure
• Structures allow us to keep related data
  referring to individual members together
• Strings, integer, and floating-point variables
  may be grouped together into one structure.
• In effect, we have created our own customized
  data type.
• The semicolon after the closing curly brace is
  required

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Composite Data Types
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Using the new data structure

• The structure definition should be placed above
  the main function of a program but below the
  compiler directives
• Declare an actual variable of this
  programmer-created data type within a function
  (such as main) in order to make use of this
  structureDone with a declaration statement like
• Student freshmen
• This reates a variable called freshmen of the
  data type Student

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Assigning values to the structure

• To assign a grade point average (GPA) of 3.4 to
  the gpa member of the variable freshmen, use the
  statement
• freshmen.gpa 3.4
• The period (.) that is used between the variable
  name freshmen and the member gpa is called the
  dot operator.
• The dot operator simply us to reference
  individual members of a structure

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Composite Data Types
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Nested Structures

• You can use a previously defined structure as a
  member of another structure
• Address is nested inside of the Customer
  structure.
• Since Address is used within Customer, the
  structure definition for Address must be placed
  above Customer in order to avoid compile errors
• struct Address string street string
  city string state int zip struct
  Customer string name string phone
  Address homeAddress Address businessAddress
  

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Pointer Use in C.

• A pointer is a variable or constant that holds a
  memory address
• a) Hexadecimal numbers are used for representing
  memory locations

216793 216794 216801 iptr 216801 3 i 216802
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Classes

• The definition of an object is know as a class
• It is similar to using basic data structures in
  C
• When you declare an object, you are said to have
  instantiated it (given it instances)
• Objects are members of a class
• Paul Millis, George Bush and George Washington
  being members of the human being class
• The design of a class is as important as its
  implementation