1. 1
Programming in C++
The Turbo C++ Environment
C++ Program Structure
Modular Programming with Functions
C++ Control Structures
Advanced Data Types
Classes

2. 2
Turbo C++ Environment
Windows based product
Integrated Development Environment (IDE)
– editor
– compiler
– linker
– debugger

3. 3
Structure of a C++ Program
preprocessor directives
main function header
{
declare statements
statements
}

4. 4
Using the Turbo C++ IDE
tool bars
menu
editor

5. 5
Using the Turbo C++ IDE (2)
compiling
linking
executing

6. 6
Developing Programs
Understand the problem
Design a solution to the problem
– including test cases and the solutions to the test
cases
Implement and document
– Translate the solution to a programming
language

7. 7
Developing Programs (2)
Verify
– Test and debug the solution
» using test cases from design phase
Maintain

8. 8
Problem Solving (1)
consider a trapezoid -- 4 sided figure in which
two sides are ||, the area is 1/2 the product
of the height and the sum of the lengths of
the two bases.
b1
h
b2
Area = (b1 + b2)h/2

9. 9
Problem Solving -- Trapezoid
Pseudocode
input b1
input b2
input height
bases = b1 + b2
area = bases * h /2
output area

10. 10
Problem Solving (2)
consider finding the area and circumference
of a circle
pi = 3.14159
area = pi * radius2
circumference = 2 * pi * radius

11. 11
Problem Solving -- Circle
Functions Pseudocode
pi = 3.14159
input radius
circum = 2 * pi * radius
area = pi * radius * radius
output area
output circum

12. 12
Problem Solving (3)
consider converting temperatures from
Centigrade to Fahrenheit (or vice versa)
where
c = 5/9(f-32)
f = 9/5c + 32

13. 13
Problem Solving --Temperature
Conversion Pseudocode
input temp
input scale
if scale = = ‘f’
newtemp = 5/9 (temp-32)
else
newtemp = 9/5 temp + 32
output newtemp

14. 14
Problem Solving (4)
consider sales commissions based upon the
number of sales made during the time
period
$8 per sale for 15 sales
$12 per sale = 15 sales
$16 per sale 15

15. 15
Problem Solving -- Commission
Pseudocode
quota = 15
input number_sales
if number_sales quota
rate = 8
else if number_sales == quota
rate = 12
else rate = 16
com = rate * number_sales
output com

16. 16
Problem Solving -- Commission
Pseudocode Multiple
Salespeople
quota = 15
input number_salespeople

17. 17
Problem Solving -- Pseudocode
Multiple Salespeople (2)
loop number_salespeople times
input number_sales
if number_sales quota
rate = 8
else if number_sales == quota
rate = 12
else rate = 16
com = rate * number_sales
output com

18. 18
Exercise -- GO
Develop a series of problems for the students
to do using each of the statement types

19. 19
Introduction to the C++
Language
keywords
– C++ is case-sensitive
identifiers
– can not be keywords
comments
– enclosed in /* */ multi-line
– start with // single line

20. 20
Preprocessor Statements
library header files -- #include
-- system library
#include iostream.h
“ “ -- personal library
#include “apstring.h”

21. 21
Data Types and Declarations
declare statement
– allocates memory and assigns “name”
– data type name [= initial value];
int -- 2 bytes
float -- 4 bytes
double -- 8 bytes
char -- enclosed in ‘ ‘

22. 22
User Defined Data Types
class -- mechanism to establish new data
types
ap classes
– string
» apstring.h apstring.ccp
– bool
» bool.h

23. 23
Example Declare Statements
int a;
int a,b,c;
float x,
y;
double average = 0.0;
char answer = ‘Y’;
bool another;
bool more = false;
apstring name;
apstring
class = “C++”;

24. 24
Input and Output Statements
#include iostream.h
cout -- output
insertion character
cin -- input
extraction character

25. 25
Using APSTRING Class
#include “apstring.h”
– entire path
create project
– place apstring and program in project
– you will need a different project for each
program

26. 26
Input and Output Statements (2)
COUT -- control codes
– way of inserting placement control
– n -- new line
– t -- tab
iomanip.h
– contains more formatting methods

27. 27
Arithmetic in C++
operator precedence
( )
*, /, % (left to right)
+, - (left to right)
integer arithmetic
– operations involving integers yielding integer
results
– truncation on integer division
– % -- modulo operator

28. 28
Arithmetic in C++ (2)
mixed mode arithmetic
– operands of different data types
– hierarchy double/float/int
» highest mode is used
» determined on a operation by operation basis

29. 29
Assignment Statements
assignment operator =
– operator precedence and mixed mode
arithmetic hold
combination operators
+=, -=, *=, /=, %=
variable = expression;

30. 30
Increment and Decrement
Statements
special operators which add or subtract one
from a variable
– more efficient (generates inc, dec)
a++; == a = a+1;
a--; == a = a -1;
postfix (a++;) (a--;)
– done after the expression is evaluated
prefix (++a;) (--a;)
– done prior to evaluating the expression

31. 31
Type Casting
changes the evaluation data type of the
expression
– does not change the data type of the variable
(data type)
– (int)
– (float)
– (apstring)

32. 32
Programming Problems
convert distance in miles to distance in
kilometers and meters
– 1 mile = 1.61 km, 1 km = 1000 meter
convert a temperature in Celsius to Kelvin
– -273.15oC = 0oK
convert a temperature in Fahrenheit to
Kelvin
– -459.67oF = 0oK

33. 33
Mathematical Functions (math.h)
code reuse
sqrt, pow, exp, log, log10
abs, ceil, floor
trigonometric functions

34. 34
Programming Problems
determine the volume of a sphere with an
input radius
– volume = (4 * pi * radius3)/3
determine the area of a triangle when given
length of two sides and the included angle
in degrees
– degrees = 180 * radians / pi
– area = side1 * side2 * sin (radians) / 2

35. 35
Programming Problems (2)
determine the distance from a point on the
Cartesian plane to the origin
– distance = sqrt (x2 + y2)

36. 36
Exercise -- GO
Implement the sequential problems developed
in the first exercise

37. 37
Modular Programming with
Functions
designed in small segments
each segment implemented as a function
– sqrt, pow, sin
self contained
– requires input through parameters
– sends output through name
Abstraction
– know what the function does and what it needs
to do its task
– not how the function works

38. 38
Modular Programming with
Functions (2)
allows for reuse
eliminates redundancy
allows for team development
simplifies logic

39. 39
Form of a Function
[return data type] Function name (parameter list)
{
[declarations]
statements
[return ]
}

40. 40
Types of Functions
no input, no return value
– void
input but no return value
both input and output
no input but returns a value

41. 41
Example -- Circle Functions
calculate the area and circumference of a
circle of an input radius
– input radius
– calculate area
– calculate circumference
– output results
invoke the functions
– use name and parameters in an expression
functions must be defined before they can
be used

42. 42
Example -- Pythagorean Triples
Pythagorean Triple are the three sides of a
right triangle a,b,c
– a2 + b2 = c2
given m and n, such that mn we can
generate the triples
– a = m2 - n2
– b= 2mn
– c = m2 + n2

43. 43
Call by Value
on invocation the value of the actual
parameter is copied into the formal
parameter
when the function terminates the value IS
NOT copied back to the actual parameter
can not change the value of a parameter
within the function

44. 44
Example Call by Value
#include iostream.h
int test (int n)
{
int i = 5;
n +=i;
return (n);
}
void main (void)
{
int n=1, i;
i = test (n);
cout i “ = “
n endl;
}

45. 45
Example Call by Value (2)
main test
n
i
n
i
1
6
1 6
5

46. 46
Functions -- Pass by Reference
returns 0 or 1 value through name
need to return more than 1
– swap the values of two variables
change the values of parameters
– bank deposit or check
pass the “name” of the parameter rather
than its value so that the function uses the
same memory location as the actual
parameter

47. 47
Reversing Order -- Swap
if (num1 num2)
{
temp = num1;
num1 = num2;
num2 = num1;
}

48. 48
Reference Parameters
Parameter which shares the memory of the
actual parameter rather than declare new
memory and copy the actual’s value into it
Parameter declaration
int x;
– x is an alias for the actual integer parameter
double y
– y is an alias for the actual double parameter

49. 49
Function Swap
void swap (int num1, int num2)
{ int temp;
temp = num1;
num1 = num2;
num2 = temp;
}
if a b
swap (a,b); to invoke the function

50. 50
Call by Value vs Reference
Use reference vs return type
– all input
– when need to return more than 1 value
– always have return type void
Use value
– all other cases
– no side effects

51. 51
Exercise
modify circle.cpp to use reference where
appropriate
modify pyth.cpp to have compute_sides

52. 52
Programming Problem --
Functions
program to convert Fahrenheit to Celsius,
Fahrenheit to Kelvin
– input the temperature in Fahrenheit
– use functions
» input Fahrenheit temperature
» convert to Celsius
» convert to Kelvin
» output the results

53. 53
Programming Problem --
Functions
Translate US prices from pennies per pound
to Canadian prices dollars per kilogram
– 1 pound = .4536 kilograms
– 1 dollar US = 1.26 dollars Canadian
Input 5 words, echoing each as it is input
and display the average length (number of
characters) per word

54. 54
Exercise -- GO
Implement all previous programs using
modular design and reference and value
parameters as appropriate

55. 55
Function Prototypes
a function must be declared before it can be
used
placed functions at top of program
create prototype (declaration of interface),
place it at the top and the functions’
implementation can be placed after the main
function
[return value] function name (parameter
list);
float get_radius ();

56. 56
Overloading
function names can be overloaded
– different interfaces
– compiler can determine which to execute
operators can be overloaded as well

57. 57
Selection Structures
execute a group of statements based upon a
condition being true or false
if (condition)
statement;
if (condition)
{ statement(s);
}
conditions -- relational operators
, , =, =, = =, !=

58. 58
Simple Selection Examples
if (hours 40)
cout “overtime!n”;
if (cost 30000)
{
tax = (cost - 30000) * tax_rate;
cout “n for a car costing “ cost
“a luxury tax of “ tax “ is due ”;
}

59. 59
Selection -- IF ELSE
if (condition)
statement;
else
statement;
if (condition)
{ statements;
}
else
{statements;
}

60. 60
If ELSE -- Examples
if (xy)
max = x;
else
max = y;

61. 61
If ELSE -- Examples (2)
if (hours = 40)
gross_pay = wage * hours;
else
{
overtime_hours = hours -40;
overtime_pay = wage * overtime_hours * 1.5;
gross_pay = wage * 40 + overtime_pay;
}

62. 62
Programming Example
find the reciprocal of an integer
undefined for 0
– attempt to divide by 0 will cause program
termination
recip.cpp

63. 63
Programming Exercise
Modify the program which finds the roots
of the quadratic equation so that it will not
error terminate
– quad.cpp

64. 64
Logical Operators
combine two or more relational operators to
create complex relations
AND --
OR -- ||
NOT -- !
precedence before ||

65. 65
Conditional Operators --
Examples
if (temp_type = = ‘F’ || temp_type = = ‘f’)
{
centigrade = convert_cent (temp);
kelvin = convert_kelvin (temp);
}
If (num 0 num 10)
{
cout “single digit numbern”;
}

66. 66
Short Circuiting
efficient evaluation of Boolean expression
AND
– the first relational expression which evaluates
false terminates the evaluation-- result false
OR
– the first relational expression which evaluates
as true terminates the evaluation -- result true

67. 67
Short Circuiting (2)
determine if a number is divisible by
another number
if the second number is 0 -- error
termination
if (a != 0 b % a == 0)
if a = 0 the second expression is not
evaluated

68. 68
Programming Example
determining leap years
leap years occur every 4 years, if the year is
divisible by 4
– only valid for non-centennial years
centennial year (divisible by 100) which is
divisible by 400

69. 69
BREAK statement
allows program to leave a control structure
form -- break;

70. 70
Multiple Selection -- Switch
test the value of a single integer type and
perform different blocks of statements
based upon the value

71. 71
Multiple Selection -- Switch
Form
switch (expression)
{ case value 1:
statement(s);
break;
case value 2:
statement (s);
break; ....
[default:
statement(s);
break;]}

72. 72
Example Switch Statement
determine if a value is -1, 0, or 1-4
cin value;
switch (value)
{
case -1:
cout “value = -1n”;
break;
case 0:
cout “value = 0n”;
break;

73. 73
Example Switch Statement Con’t
case 1:
case 2:
case 3:
case 4:
cout “value in range 1-4n”;
break;
default:
cout “value is -1 or 4n”;
}

74. 74
Example Programming Problem
color compliments
clswitch.cpp

75. 75
Programming Problem
complete temperature conversion program
accepts as input a temperature and a type
and converts it to the other two temperature
types
prints an error message if unknown type
accepts both upper and lower case input

76. 76
Exercise -- GO
Implement the selection statement problem
solving problems

77. 77
Repetition Statements
ability to repeatedly execute blocks of
statements
two types of loops
– count controlled
» executed a set number of times
– event driven
» executed until a certain event occurs
» pre-test and post-test loops

78. 78
While Loop
form
while (condition)
{
statement(s);
}
event driven loop

79. 79
While Loop (2)
pre-test (0) loop
– test the condition
» if true execute the loop
» if false exit loop
» loop can be executed 0 times

80. 80
Example While Loop
i = 5;
while (i 0)
{ cout i endl;
i--;
}

81. 81
Programming Example
taking averages
enter values to be averaged until sentinel is
entered (0)
– event which terminates loop
ave.cpp

82. 82
Controlling Input
0 is in the set to be averaged
– must use some key defined value to signal end
of input
– CRTL Z
get()
– cin.get()
– accepts a single value as input
– prompt for CRTL (^) Z

83. 83
Do While Loop
event driven loop
always executes at least once (1 loop)
post test loop
form
do{
statement(s);
}while (condition);

84. 84
Do While Loop (2)
executes the loop
tests the condition
– if true executes the loop again
– if false exits the loop

85. 85
Do While Example
add the numbers from 1 to 5
sum = 0;
i = 1;
do{
sum += i;
i ++;
}while (i = 5);

86. 86
Programming Example
display square of input value
user prompt to continue
squares.cpp

87. 87
Programming Example -- Circle
Functions
robust programming
– user friendly/user forgiving
Area and Circumference of circle
– radius can not be =0
– present error message and re-prompt for input
until it is valid
– circleif.cpp

88. 88
Programming Exercise --
Pythagorean Triples
robust example
– m n and both 0
give meaningful error message

89. 89
For Loop
counted loop -- set number of times
iterates through a set of values
for (initial expression;
condition;
loop expression)
{ statement(s);
}

90. 90
For Loop (2)
initial expression -- starting point, executed
once before the loop begins
condition -- evaluated each time through the
loop (pre test)
– exit -- false
– execute -- true
loop expression -- statement(s) executed at
the bottom of the loop

91. 91
Example For Loop - I
Countdown
for (i = 1; i=5; ++i)
{
cout i endl;
}

92. 92
Example For Loop - II
sum numbers 1-5
for (sum = 0, i = 1; i = 5; ++i)
{
sum += i;
}

93. 93
Programming Examples
Factorials
– fact.cpp
– change fact to be integer (see what happens)
temperature conversions
– temps.cpp
generating random numbers
– random.cpp

94. 94
Boolean Variables
Turbo C++ does not have Boolean
– bool.h -- apclass
– 0 false, 1 true
bool flag
– if flag (if 0 false, non 0 true)
– while !flag
flags.cpp

95. 95
Programming Exercise
maintain check book balance
modular
$15 service fee for bad check
– display message
final balance on exit

96. 96
Nesting Control Structures
both selection and repetition statements can
be nested for complex execution
if else if
– else matches closest un-elsed if
all looping structures can be nested
regardless of type

97. 97
Example If else if -- Sales
Quotas
if (num_sales quota)
rate = low_rate;
else if (num_sales = quota)
rate= ave_rate;
else rate = high_rate;

98. 98
Example Nested Loops
cout “enter the number to sum to, 0 to
end”;
cin num;
while (num != 0)
{ for (sum=0, i=1; i=num;++i)
sum += num;
cout “the sum of the numbers 1 - ....
cout “enter the number to sum to ...
cin num);} /*end while*/

99. 99
Nesting Control Structures
Programming Examples
counting number of letter grades
– aven.cpp
printing multiplication tables
– table.cpp
circle functions
– circleof.cpp

100. 100
Programming Exercise
Modify the average program so that more
than 1 set of averages can be determined
Modify the Pythagorean triples so that an
unlimited number of triples can be
generated
Modify finding roots of a quadratic
equation so that all root types are
determined

101. 101
Enumeration Types
user defined data type
– enum statement
– define the domain
enum bool {false, true};
– bool -- name of data type
– false, true -- domain
integers
– false = 0, true =1

102. 102
Lines in Cartesian Plane
perpendicular, parallel or intersecting
slope
enumeration type can be used
– parameters
– return types
lines.cpp

103. 103
Exercise -- GO
Implement any remaining problem solving
programs.
Be sure have a complete set identifying all
structures including enumeration types.

104. 104
Composite Data Structures
construct that can access more than one data
item through a single name
Array -- homogenous data type
Structure -- heterogeneous data type

105. 105
ArraysVectors
collection of data components
all of same data type
are contiguous
accessed
– entire array (name)
– individual component (subscript)

106. 106
Declaring Arrays
int x[5]
– declares a 5 element array of integers
» x[0], x[1], x[2], x[3], x[4]
int x[2][5] -- two dimensional array
int x [2] [5] [5] -- three dimensional array
size must be declared at compile time
– can not int size, int x[size]
– can
» #define max_size 100
» int x[max_size]

107. 107
Referencing Arrays
elements
– float ave_temp [12]
» ave_temp [0] -- Jan
» ave_temp [11] -- Dec
» ave_temp [i+2]
no arrays bounds checking
– “fast” code

108. 108
Initializing Arrays
int x[5] = {12,-2,33,21,31};
int height [10] = {60,70,68,72,68};
– rest 0
float g[] = {3.2,5.7};
– size is set to 2
a 250 element array all to 1
int x[250];
for (i =0; i=249; i++)
x[i] = 1;

109. 109
Using Arrays
data must be passed more than once
– array1.cpp
implement vectors or matrices
– array2.cpp
data comes in haphazard order
– string example

110. 110
Passing Arrays to Functions
pass an element
– treated as any single variable of that type
» pass by value
pass the entire array
– use the name without any subscripting
– pass by reference
» pass the address and the actual memory locations of
the actual array are used by the function
» any change made to the elements of the array by the
function WILL be noted in the main program

111. 111
Programming Problem
Input a set of exam scores for a class
– calculate and display
» average
» high grade
» low grade
» those grades which were above the average
– have number of grades entered determined by
the # of values input rather than prompt for
class size

112. 112
Programming Problem
Using an enumeration type for months of
the year
– calculate the average rainfall
– display those months with average rainfall
amounts

113. 113
Structures
Heterogeneous data type
– logically related set of items which can be
accessed either on an individual item basis or
all at once through structure’s name
– fields can be of any data type (different ones),
user defined as well

114. 114
Example Structure
struct GRADES
{ apstring name;
int midterm;
int final;
float assigns;
float sem_ave;
char letter_grade;};
GRADES student1, student2;

115. 115
Operations on Structures
Assignment
– entire structures done by common elements, in
order
– single element -- data type
Initialization
– on declare
» FRACTION num1 = {1,2};
» GRADES student1 = {“john Doe”,90,80,70,80};

116. 116
Structures and Functions
An element is passed to a structure in the
same way any simple variable is passed
– by value (default) or by reference (forced)
– student.cpp
An entire structure is passed
– by value (default)
– by reference (force) employee.cpp
A function can return a structure variable

117. 117
“Arrays” and Structures
Structures can contain vectors, apstring
– apstring name
– apvectorint exams(3)
vectors of structures
– apvectorGRADES class(60);
» 60 students in class
» class[0].name class[0].final
» class[59].name class[59].final

118. 118
Hierarchical Structures
Structures can contain structures
typedef struct
{char last [15];
char first [15];
char middle;} NAME;
typedef struct
{NAME stu_name;
…} STUDENT;

119. 119
ArraysVectors
collection of data components
all of same data type
are contiguous
accessed
– entire array (name)
– individual component (subscript)

120. 120
Declaring Vectors
#include “a:apvector.h”
apvectorint v1(10);
– declares a 10 element integer vector
– v1[0], v1[1], v1[2]….v1[9]
apvectorint v2(10,0);
– declares a 10 element integer vector
– all elements are initialized to 0
– v2[0]=0, v2[1]=0…..v2[9]=0

121. 121
Declaring Vectors (2)
apvectorapstring (25);
– declares a vector of 25 strings
– each is “empty” string
can be user defined data types

122. 122
Accessing Elements
v1[1]
– second element of the vector
v1[9]
– last element of the vector
v1[1] += 2;
high = v1[3];

123. 123
Assignment -- APVECTOR
Apvectorint v1(10), v2(20);
v1 = v2;
– v1 will be “reallocated” at a size of 20
– v1[0] = v2[0]
– ….
– v1[19] = v2[19]
corresponding elements will be assigned

124. 124
Member Functions -APVECTOR
User defined data type -- class
length() -- capacity of vector
– size changes as needed
– returns current size as an integer
– object.length()
» v1.length() = 20
» v1 still ranges from 0-19
for (i=0;iv1.length();i++)
cout v1[i] endl;

125. 125
Vectors as Parameters
elements are considered same as any single
variable
entire vector
– pass by value or by reference
– more efficient to pass by reference
– avoid side effects
» const reference parameter

126. 126
Using Vectors
data must be passed more than once
– vect1.cpp
implement vectors or matrices
– vect2a.cpp
data comes in haphazard order
– string example
enumeration types and vectors
– rainenum.cpp

127. 127
Matrices
two dimensional array
problems with C++ arrays are doubled in
two dimensions
APMATRIX
– #include “a:apmatrix.h”
– can automatically be “resized”
– subscript checking

128. 128
Declaring Matrices
apmatrixint imat (3,3)
– imat[0][0] ....imat [2][2]
apmatrixint imat2(3,3,0)
– all elements are initialized to 0
can be any system or user defined data type

129. 129
Referencing Elements
imat[1][2] = 7;
score = imat [i][j];
if subscript is out of bounds (either of them)
program error terminates

130. 130
Assignment -- APMATRIX
apmatrixint imat2(10,10);
imat = imat2;
– imat 3x3
– imat2 10x10
– after assignment imat 10x10
– assigns corresponding elements

131. 131
APMATRIX--Member Functions
numrows() -- returns the number of rows
– imat.numrows() == 10
numcols() -- returns the number of columns
– imat.numcols() == 10
for (r=0;rimat.numrows();r++)
for (c=0;cimat.numcols();c++)
cout imat[r][c];

132. 132
Programming Problem
Create “resuable” functions for matrix
addition and multiplication
– matrix.h
– matrix.cpp
– use_matrix.cpp

133. 133
ADT -- complex numbers
struct COMPLEX
{ double real;
double imag;};
operations -- input, output, add, subtract,
mult, divide, absolute value
package together in include file

134. 134
Class -- User Defined Data Type
encapsulate data and functions
information hiding
– public vs private
can be inherited
– structures can not

135. 135
Public VS. Private
client programs can use the member
functions which “come with” a class
through the public interface
client program CAN NOT access any
function or data member declared private
– information hiding
– if can’t access it, can’t modify it
– more maintainable -- fewer side effects

136. 136
Class Definition
class class_name
{public:
member functions
private:
data members
};

137. 137
Data Members
Pieces of information which the class
maintains
– states
» date -- month, day, year
» complex number --- real, imaginary
» fraction -- numerator, denominator
» student -- name, ssn, address, etc
Private-- only the functions of the class
have access to them

138. 138
Member Functions
Services provided by the class to
manipulate the data members
Public -- can be used by any “client”
program
Have access to the data members
Constructors, Accessors, Mutators, and
Operations

139. 139
Constructors
Automatically invoked by the system when
an object of the class is declared
specify the initial values to be given to the
data members
function with the same name as the class
itself with no return type of any kind
can be overloaded

140. 140
Accessors
Return the value of a data member
Const functions as they do not change the
value of any data member
Necessary since no “outside” function can
access the data members

141. 141
Mutators
Modify one or more of the data members
used by client programs to modify the data
members, since client programs can not
access the data members directly

142. 142
Operations
Provide services of the class
perform calculations, etc using data
members
necessary since the data members are not
accessible to the client programs

143. 143
Date Class
Data members
– int day, int month, int year
Constuctor
– allow date to be set when the object is declared
– or to use default values
small implementation of the class
– demonstration purposes only

144. 144
Interface of the Date class
Definition of the class
available to client programs/ers
.h file
declaration of the data members
interfaces of the member functions
the object receiving the message to invoke
the member function is the one that the
function operates upon

145. 145
Date Class Implementation
.cpp file
the implementation of all member functions
scope resolution operator ::
– since the function implementations are in a
separate file need to tie them back to the class
or they will not have access to the data
members

146. 146
Client Program
Declares an object of the data type
– Date today;
Invoke a member function
– object.function_name();
– object which receives the message is the one on
which the function the function operators
» v1.resize();
» v1.length();

147. 147
Constructor
Default initial values for parameters
– if the parameters are omitted the initial value of
the fraction on declaration is 1/1
initialization list
– special form of the constructor which allows
the data members to be set within the interface
(.h file)

148. 148
Fraction Class
Represents rational
numbers
constructor
– initializes object to 1/1
accessors
– reduce
– print_fraction
Mutators
– input_fraction
operations
– add, subtract, multiply,
divide
gcd
– needed by class to do
its work

149. 149
Member vs Friend functions
Member function must be invoked with
object receiving message
friend function stands separate
– it still has access to the data members
– does not need an object to be invoked
– used for binary operators which do not modify
their parameters (overloading)
defined in interface as friend

150. 150
Complex Number Class
class COMPLEX
{public:
COMPLEX(int r=0,int i=0);
int real() const;
int imaginary() const;
COMPLEX add_complex
(const COMPLEX l, const COMPLEX r);

151. 151
Complex Number Class Con’t
COMPLEX sub_complex
(const COMPLEX l, const COMPLEX r);
COMPLEX mult_complex
(const COMPLEX l, const COMPLEX r);
COMPLEX div_complex
(const COMPLEX l, const COMPLEX r);

152. 152
Complex Number Class -- Con’t
void set_real (double);
void set_imag(double);
private:
double real;
double imag;
};

153. 153
Member vs Friend functions
Member function must be invoked with
object receiving message
friend function stands separate
– it still has access to the data members
– does not need an object to be invoked
– used for binary operators which do not modify
their parameters (overloading)
defined in interface as friend

154. 154
Inlining
Used to provide an implementation within
the interface
Only use on “small simple functions” which
either simply set data members or simple
calculations which return values

155. 155
This pointer
Refers to the object receiving the message
*this == value
– used in functions which modify the object
receiving the message +=,-=,*=,/=

156. 156
File I/O
Input and output are done through streams:
istream and ostream (fstream.h)
– cin -- istream -- iostream.h
– cout -- ostream -- iostream.h
4 steps to using files
– declare an object of the appropriate stream
open the stream
– connects the external file with the stream
(buffer)
– stream.open(filename);

157. 157
File I/O(2)
Input but from the stream declared
rather than from cin
output but from the stream declared
rather than cout
close file
– stream.close();