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Programming in C++
The Turbo C++ Environment C++ Program Structure Modular Programming with Functions C++ Control Structures Advanced Data Types Classes
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Turbo C++ Environment
Windows based product Integrated Development Environment (IDE)
– editor– compiler– linker– debugger
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Structure of a C++ Program
preprocessor directives
main function header
{declare statements
statements
}
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Using the Turbo C++ IDE
tool bars menu editor
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Using the Turbo C++ IDE (2)
compiling linking executing
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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
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Developing Programs (2)
Verify– Test and debug the solution
» using test cases from design phase
Maintain
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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.
b2
h
Area = (b1 + b2)h/2
b1
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Problem Solving -- Trapezoid Pseudocode
input b1
input b2
input height
bases = b1 + b2
area = bases * h /2
output area
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Problem Solving (2)
consider finding the area and circumference of a circlepi = 3.14159
area = pi * radius2
circumference = 2 * pi * radius
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Problem Solving -- Circle Functions Pseudocode
pi = 3.14159
input radius
circum = 2 * pi * radius
area = pi * radius * radius
output area
output circum
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Problem Solving (3)
consider converting temperatures from Centigrade to Fahrenheit (or vice versa) where
c = 5/9(f-32)
f = 9/5c + 32
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Problem Solving --Temperature Conversion Pseudocode
input temp
input scale
if scale = = ‘f’newtemp = 5/9 (temp-32)
elsenewtemp = 9/5 temp + 32
output newtemp
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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
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Problem Solving -- Commission Pseudocode
quota = 15
input number_sales
if number_sales < quotarate = 8
else if number_sales == quota
rate = 12
else rate = 16
com = rate * number_sales
output com
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Problem Solving -- Commission Pseudocode Multiple Salespeople
quota = 15
input number_salespeople
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Problem Solving -- Pseudocode Multiple Salespeople (2)
loop number_salespeople times
input number_sales
if number_sales < quotarate = 8
else if number_sales == quota
rate = 12
else rate = 16
com = rate * number_sales
output com
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Exercise -- GO
Develop a series of problems for the students to do using each of the statement types
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Introduction to the C++ Language
keywords– C++ is case-sensitive
identifiers– can not be keywords
comments– enclosed in /* */ multi-line – start with // single line
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Preprocessor Statements
library header files -- #include< > -- system library
#include <iostream.h>
“ “ -- personal library#include “apstring.h”
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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 ‘ ‘
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User Defined Data Types
class -- mechanism to establish new data types
ap classes– string
» apstring.h apstring.ccp
– bool» bool.h
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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++”;
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Input and Output Statements
#include <iostream.h>
cout -- output
<< insertion character
cin -- input
>> extraction character
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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
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Input and Output Statements (2)
COUT -- control codes– way of inserting placement control– \n -- new line – \t -- tab
iomanip.h– contains more formatting methods
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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
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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
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Assignment Statements
assignment operator =– operator precedence and mixed mode
arithmetic hold combination operators
+=, -=, *=, /=, %= variable = expression;
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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
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Type Casting
changes the evaluation data type of the expression– does not change the data type of the variable
(data type)– (int) – (float)– (apstring)
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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
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Mathematical Functions (math.h)
code reuse sqrt, pow, exp, log, log10 abs, ceil, floor trigonometric functions
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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
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Programming Problems (2)
determine the distance from a point on the Cartesian plane to the origin– distance = sqrt (x2 + y2)
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Exercise -- GO
Implement the sequential problems developed in the first exercise
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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
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Modular Programming with Functions (2)
allows for reuse eliminates redundancy allows for team development simplifies logic
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Form of a Function
[return data type] Function name (parameter list){
[declarations]
statements[return ]
}
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Types of Functions
no input, no return value – void
input but no return value both input and output no input but returns a value
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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
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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 m>n we can generate the triples– a = m2 - n2
– b= 2mn– c = m2 + n2
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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
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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;}
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Example Call by Value (2)
main test
n
i
n
i
1
6
1 6
5
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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
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Reversing Order -- Swap
if (num1 < num2)
{
temp = num1;
num1 = num2;
num2 = num1;
}
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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
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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
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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
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Exercise
modify circle.cpp to use reference where appropriate
modify pyth.cpp to have compute_sides
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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
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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
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Exercise -- GO
Implement all previous programs using modular design and reference and value parameters as appropriate
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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 ();
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Overloading
function names can be overloaded– different interfaces– compiler can determine which to execute
operators can be overloaded as well
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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
<, >, <=, >=, = =, !=
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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 ”;
}
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Selection -- IF ELSE if (condition)
statement;
else
statement; if (condition)
{ statements;
}
else
{statements;
}
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If ELSE -- Examples
if (x>y) max = x;
else
max = y;
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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;
}
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Programming Example
find the reciprocal of an integer undefined for 0
– attempt to divide by 0 will cause program termination
recip.cpp
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Programming Exercise
Modify the program which finds the roots of the quadratic equation so that it will not error terminate– quad.cpp
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Logical Operators
combine two or more relational operators to create complex relations
AND -- && OR -- || NOT -- ! precedence && before ||
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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 number\n”;
}
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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
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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
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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
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BREAK statement
allows program to leave a control structure form -- break;
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Multiple Selection -- Switch
test the value of a single integer type and perform different blocks of statements based upon the value
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Multiple Selection -- Switch Form
switch (expression)
{ case value 1:
statement(s);
break;
case value 2:
statement (s);
break; ....
[default:
statement(s);
break;]}
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Example Switch Statement
determine if a value is -1, 0, or 1-4cin >> value;
switch (value)
{
case -1:
cout << “value = -1\n”;
break;
case 0:
cout << “value = 0\n”;
break;
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Example Switch Statement Con’t
case 1:
case 2:
case 3:
case 4:
cout << “value in range 1-4\n”;
break;
default:
cout << “value is < -1 or > 4\n”;
}
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Example Programming Problem
color compliments clswitch.cpp
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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
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Exercise -- GO
Implement the selection statement problem solving problems
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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
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While Loop
formwhile (condition)
{
statement(s);
} event driven loop
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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
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Example While Loop
i = 5;
while (i > 0)
{ cout << i << endl;
i--;
}
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Programming Example
taking averages enter values to be averaged until sentinel is
entered (0)– event which terminates loop
ave.cpp
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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
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Do While Loop
event driven loop always executes at least once (1 loop) post test loop form
do{
statement(s);
}while (condition);
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Do While Loop (2)
executes the loop tests the condition
– if true executes the loop again– if false exits the loop
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Do While Example
add the numbers from 1 to 5
sum = 0;
i = 1;
do{
sum += i;
i ++;
}while (i <= 5);
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Programming Example
display square of input value user prompt to continue squares.cpp
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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
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Programming Exercise -- Pythagorean Triples
robust example– m > n and both > 0
give meaningful error message
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For Loop
counted loop -- set number of times iterates through a set of values
for (initial expression;
condition;
loop expression)
{ statement(s);
}
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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
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Example For Loop - I
Countdown
for (i = 1; i<=5; ++i)
{
cout << i << endl;
}
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Example For Loop - II
sum numbers 1-5
for (sum = 0, i = 1; i <= 5; ++i)
{
sum += i;
}
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Programming Examples
Factorials– fact.cpp– change fact to be integer (see what happens)
temperature conversions– temps.cpp
generating random numbers– random.cpp
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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
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Programming Exercise
maintain check book balance modular $15 service fee for bad check
– display message final balance on exit
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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
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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
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*/
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Nesting Control Structures Programming Examples
counting number of letter grades– aven.cpp
printing multiplication tables– table.cpp
circle functions– circleof.cpp
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
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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
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Lines in Cartesian Plane
perpendicular, parallel or intersecting slope enumeration type can be used
– parameters– return types
lines.cpp
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Exercise -- GO
Implement any remaining problem solving programs.
Be sure have a complete set identifying all structures including enumeration types.
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Composite Data Structures
construct that can access more than one data item through a single name
Array -- homogenous data type Structure -- heterogeneous data type
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Arrays\Vectors
collection of data components all of same data type are contiguous accessed
– entire array (name)– individual component (subscript)
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]
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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
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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;
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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
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
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
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Programming Problem
Using an enumeration type for months of the year– calculate the average rainfall– display those months with < average rainfall
amounts
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
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Example Structure
struct GRADES
{ apstring name;
int midterm;
int final;
float assigns;
float sem_ave;
char letter_grade;};
GRADES student1, student2;
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
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
“Arrays” and Structures
Structures can contain vectors, apstring– apstring name– apvector<int> exams(3)
vectors of structures– apvector<GRADES> class(60);
» 60 students in class
» class[0].name class[0].final
» class[59].name class[59].final
118
Hierarchical Structures
Structures can contain structures
typedef struct
{char last [15];
char first [15];
char middle;} NAME;
typedef struct
{NAME stu_name;
…} STUDENT;
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Arrays\Vectors
collection of data components all of same data type are contiguous accessed
– entire array (name)– individual component (subscript)
120
Declaring Vectors
#include “a:apvector.h” apvector<int> v1(10);
– declares a 10 element integer vector– v1[0], v1[1], v1[2]….v1[9]
apvector<int> 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
Declaring Vectors (2)
apvector<apstring> (25);– declares a vector of 25 strings– each is “empty” string
can be user defined data types
122
Accessing Elements
v1[1]– second element of the vector
v1[9]– last element of the vector
v1[1] += 2; high = v1[3];
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Assignment -- APVECTOR
Apvector<int> 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
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;i<v1.length();i++)
cout << v1[i] << endl;
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
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
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
Declaring Matrices
apmatrix<int> imat (3,3)– imat[0][0] ....imat [2][2]
apmatrix<int> imat2(3,3,0)– all elements are initialized to 0
can be any system or user defined data type
129
Referencing Elements
imat[1][2] = 7; score = imat [i][j]; if subscript is out of bounds (either of them)
program error terminates
130
Assignment -- APMATRIX
apmatrix<int> imat2(10,10); imat = imat2;
– imat 3x3– imat2 10x10– after assignment imat 10x10– assigns corresponding elements
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;r<imat.numrows();r++)
for (c=0;c<imat.numcols();c++)
cout << imat[r][c];
132
Programming Problem
Create “resuable” functions for matrix addition and multiplication– matrix.h – matrix.cpp– use_matrix.cpp
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
Class -- User Defined Data Type
encapsulate data and functions information hiding
– public vs private can be inherited
– structures can not
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
Class Definition
class class_name
{public:
member functions
private:
data members
};
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Complex Number Class -- Con’t
void set_real (double);
void set_imag(double);
private:
double real;
double imag;
};
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
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
This pointer
Refers to the object receiving the message
*this ==> value– used in functions which modify the object
receiving the message +=,-=,*=,/=
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
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();
