Transcript CPS120: Introduction to Computer Science

CPS120: Introduction to
Computer Science
Structures
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
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
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;
};
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
Composite Data Types
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
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
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; };
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
…
216801
216802
3
i
iptr
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