REACH CECS 130 Final Test Review

1
REACH CECS 130 Final Test Review
2
Data

• How a computer stores data in its internal memory
• RAM (Random-Access Memory) - temporary
• ROM (Read-Only Memory) non volatile
• Store data in bytes
• How you store data temporarily
• Create variables based on fundamental types
  (bool, char, int, float)
• constants define CONSTNAME value
• sizeof()

3
Variable Types
TYPE SIZE VALUES
bool 1 byte true (1) or false (0)
char 1 byte a toz , A to Z, 0 to 9, space, tab, and so on
int 4 bytes -2,147,483,648 to 2,147,483,647
short 2 bytes -32,768 to 32,767
long 4 bytes -2,147,483,648 to 2,147,483,647
float 4 bytes - (1.2 x 10-38 to 3.4 x 1038)
double 8 bytes - (2.3 x 10-308 to -1.7 x 10308)
4
Control Statements Boolean Operators

• What do each of the following evaluate to?
• 1. long elves 8
• int dwarves 8
• if(elvesdwarves) //true or false?
• if(elves!0) //true or false?
• 2. int elves 4
• int dwarves 5
• if(dwarves gt (2/3)) //true or false?
• 3. if(0 lt x lt 99) //true or false?
• 4. if(0lt (0lt1))//true or false?

5
Control Statements Boolean Operators -Answers

• What do each of the following evaluate to?
• 1. long elves 8
• int dwarves 8
• if(elvesdwarves) //true
• if(elves!0) //true
• 2. int elves 4
• int dwarves 5
• if(dwarves gt (2/3)) //true
• 3. if(0 lt x lt 99) //true TRUE (1) and FALSE (0)
  lt 99
• 4. if(0lt (0lt1))//true

6
If statements

• if(condition)
• statement
• else if (condition)
• statement
• condition ? expr1 expr2
• ex. z ( x gt y ) ? y x
• Can we do next statement?
• (xgty) ? cout ltlt x is greater than y. cout ltlt
  x isnt greater than y.

7
Switch-case statements

• switch(expression)
• case expr1
• statement
• break
• case expr2
• statement
• break
• case expr3
• statement
• break
• default
• statements
• break

8
Loops

• while (condition)
• statements
• You need to maintain a state to break loop.
• do
• statements
• You need to maintain a state to break loop.
• while(condition)

9
Loops

• for (initialization condition expression)
• statements
• Incrementing Prefix and Postfix
• int x 5
• int y 6
• int z y //z6, y7 postfix
  operator
• int z x //z6, x6 prefix
  operator

10
Branching statements
Keyword Purpose
break Exits the nearest enclosing switch statement or iteration statement
continue Starts the next loop of the nearest enclosing iteration statement
goto Jumps to a particular place in your code
return Ends a function and returns a value
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FOR LOOP TEST

• Can you write a program that prints out the
  following?
• 0 1 2 3 4 5 6 7 8 9

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Answer

• for ( int count 0 count lt 10 count )
• cout ltltcountltlt

13
Other Challenge questions for Loops

1. Write a conditional statement that will assign
   x/y to x if y doesnt equal 0.
2. Write a while loop that calculates the summation
   of positive integers from 1 to some number n.
3. Write a conditional statement that assigns xy if
   x is even otherwise , if x is odd and y doesnt
   equal 0, assign x to x/y if neither of the
   preceding cases is true, output to the screen
   that y is equal to 0.

14
How to declare and implement functions

• Function declaration
• Function definition
• Function call

15

• include ltiostreamgt
• using namespace std
• int add(int, int)
• int main(void)
• int number1, number2
• cout ltlt Enter the first value to be summed
• cin gtgt number1
• cout ltlt \nEnter the second
• cin gtgt number2
• cout ltlt \n The sum is ltlt add (number1,
  number2) ltltendl
• int add(int a, int b)return ab

16
Functions Challenge

• Write a function, called multiply that multiplies
  two numbers and returns the result

17
Union
Output 9 3.1416

• include ltstdio.hgt
• includeltstdlib.hgt
• union NumericType
• int iValue
• long lValue
• double dValue
• int main()
• union NumericType Values // iValue 10
• Values.iValue9
• printf("d\n", Values.iValue)
• Values.dValue 3.1416
• printf("f\n", Values.dValue)
• system("pause")

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Sizeof()
19
Malloc()
Please enter how long your name is 21 Please
enter your name Nawaf Hello Nawaf
Please enter how long your name is -7 Failed
allocation memory
20
free()
21
Calloc and Realloc()

• int n
• int n1
• n( int ) calloc(5, sizeof(int)) //
  Reserves a block of memory for 5 integers
• //Decide you need to reallocate more memory later
  in the program
• n1 (int ) realloc(n, 10 sizeof(int))//allocat
  e 10 integers instead of 5
• if (n1!NULL)
• nn1
• else printf("Out of memory!")
• realloc() returns null if unable to complete or a
  pointer to the newly reallocated memory.

22
C - Files

• Do you know the syntax for each of these, used to
  read and write to data files?
• Pointers think of it as the memory address of
  the file
• fopen()
• fclose()
• fscanf()
• fprintf()

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fopen(file name, Mode)

• fopen() returns a FILE pointer back to the pRead
  variable

include ltcstdiogt Main() FILE pRead pRead
fopen(file1.dat, r) if(pRead NULL)
printf(\nFile cannot be opened\n) else
printf(\nFile opened for reading\n) fclose(p
Read)
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What does this code do?

• int main ()
• FILE pFile
• char c
• pFilefopen("alphabet.txt","wt")
• for (c 'A' c lt 'Z' c)
• putc (c , pFile)//works like fprintf
• fclose (pFile)
• return 0

25
Common Text File Modes
Mode Meaning Already Exists Does Not Exist
r Open a file for reading read from start error
w Create a file for writing destroy contents create new
a Append to a file write to end create new
r Open a file for read/write read from start error
w Create a file for read/write destroy contents create new
a Open a file for read/write write to end create new
b Combined with any mode enables user to work with binary files.(rb, wb, rb, etc.)
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fclose(file pointer)

• Pretty basic.
• Always close files when you use fopen.

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fscanf(FILE pointer, data type, variable in
which to store the value)

• Reads a single field from a data file
• s will read a series of characters until a
  white space is found
• can do
• fscanf(pRead, ss, name, hobby)

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include ltstdio.hgt Main() FILE
pRead char name10 pRead
fopen(names.dat, r) if( pRead NULL
) printf( \nFile cannot be
opened\n) else
printf(\nContents of names.dat\n)
fscanf( pRead, s, name ) while(
!feof(pRead) ) // While end of file not
reached printf( s\n, name )
// output content of name fscanf(
pRead, s, name ) // scan from file next
string fclose(pRead)
29
Quiz
Kelly 11/12/86 6 Louisville Allen 04/05/77 49 At
lanta Chelsea 03/30/90 12 Charleston
Can you write a program that prints out the
contents of this information.dat file?
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• include ltstdio.hgt
• Main()
• FILE pRead
• char name10
• char birthdate9
• float number
• char hometown20
• pRead fopen(information.dat, r)
• if( pRead NULL )
• printf( \nFile cannot be opened\n)
• else
• fscanf( pRead, ssfs, name,
  birthdate, number, hometown )
• while( !feof(pRead) )
• printf( s \t s \t f \t
  s\n, name, birthdate, number, hometown )

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fprintf(FILE pointer, list of data types,list
of values or variables)

• The fprintf() function sends information (the
  arguments) according to the specified format to
  the file indicated by stream. fprintf() works
  just like printf() as far as the format goes.

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• include ltstdio.hgt
• Main()
• FILE pWrite
• char fName20
• char lName 20
• float gpa
• pWrite fopen(students.dat,w)
• if( pWrite NULL )
• printf(\nFile not opened\n)
• else
• printf(\nEnter first name, last name, and GPA
  )
• printf(separated by spaces)
• scanf(ssf, fName, lName, gpa)

33
Quiz

• Can you write a program that asks the user for
  their
• Name
• Phone Number
• Bank account balance
• And then prints this information to a data file
  called accounts.dat ?

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C Input/Output

• Summary
• Include include ltiostreamgt directive at
  beginning of program
• Use cin to take data from user
• Use cout to display data on screen
• Display multiple strings and integers in the same
  cout statement by separating items with ltlt

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C Input/Output Example

• include ltiostreamgt
• includeltstringgt
• using namespace std
• string name
• int main(void)
• coutltltWhat is your name?
• cingtgtname
• coutltltendlltltHelloltltname.c_str()
• return 0

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Can you predict the printout?

• include ltiostreamgt
• using namespace std
• int x 25
• string str2 This is a test
• int main( void )
• coutltltTestltlt1ltlt2ltlt3
• coutltlt25 7ltltendlltltstr2.c_str()
• return 0

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Answer

• Test 1234
• This is a test

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OOP

• Declare classes
• Create objects
• 3 MAIN PRINCIPLES OF OOP
• Data abstraction hiding data members and
  implementation of a class behind an interface so
  that the user of the class corrupt that data
• Encapsulation each class represents a specific
  thing or concept. Multiple classes combine to
  produce the whole
• Polymorphism-objects can be used in more than one
  program

39
Classes

• Classes are general models from which you can
  create objects
• Classes have data members either data types or
  methods
• Classes should contain a constructor method and a
  destructor method
• See handout for example of a program that
  utilizes a class

40
Declaring Classes

• class ClassName
• memberList
• memberList can be either data member declarations
  or method declarations

41
Class Declaration Example

• Class Bow
• //data member declarations
• string color
• bool drawn
• int numOfArrows
• Bow(string aColor) //constructor
• Bow() //destructor
• //methods
• void draw()
• int fire()

42
Creating Methods

• Return_type ClassNamemethodName(argumentList)
• methodImplementation

43
Methods Creation Example

• //draws the bow
• Void Bowdraw()
• drawn true
• coutltlt The ltltcolorltltbow has been
  drawn.ltltendl

44
Advanced Data Types

• Arrays
• Pointers

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How to create arrays

• data_type array_name number-of-elements
• Two Dimensional Array
• array_type array_name number_of_ROWSnumber_of_C
  OLUMNS

46
How to create pointers

• type pointer_name
• ex. int my_int
• int my_int_pointer my_int
• Assigns the address of my_int to the pointer

47
Useful string functions

• Copying strings from one to another
• char strcpy(char p, const char q)
• char s6
• strcpy(s, Hello)
• To combine strings
• char strcat(char p, const char q)
• char s12 Hello
• strcat(s, World)

48
Useful string functions

• To copy n characters from q to the of p.
• char strncpy(char p, const char q, int n)
• char s 7 Say
• char t Hi
• strncpy (s, t, 2)
• Output
• Hiy

49
Challenge question

• Can you write a program using C that uses a FOR
  loop to initialize a 2D array that looks like the
  following 0,5,10,150,2,4,6

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Answer

• includeltiostreamgt
• using namespace std
• int main()
• int array24, , row, column
• for(row0rowlt2row)
• for(column0columnlt4column)
• if(row0)
• arrayrowcolumncolumn5
• else if(row1)
• arrayrowcolumncolumn2
• for(row0 rowlt2 row)
• for(column 0 column lt4 column )
• coutltltarrayrowcolumnltlt" "
• coutltltendl
• system("pause")
• return 0

51
Basics of C

• Basic framework for a program
• How to Comment
• How to Print
• How to store variables
• How to Print stored variables
• How to find the size of a variable
• How to convert from one data type to another
• How to Declare Constants

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Inheritance

• class aClass // Base class
• public
• int anInt
• class aDerivedClass public aClass //Derived
  class
• protected
• float aFloat

53
Inheritance for Mammals Kingdome
include ltiostream.hgt enum BREED YORKIE,
CAIRN, DANDIE, SHETLAND, DOBERMAN, LAB class
Mammal public Mammal() //
constructors Mammal() //destructor
//accessors int GetAge()const void
SetAge(int) int GetWeight() const void
SetWeight() //Other methods void Speak() void
Sleep() protected int itsAge int
itsWeight class Dog public Mammal
public Dog() // Constructors Dog() //
Accessors BREED GetBreed() const void
SetBreed(BREED) // Other methods //
WagTail() // BegForFood() protected BREED
itsBreed
Animals
Mammals
Reptiles
Horse
Dog
Hound
Terrier
Yorkie
Cairn
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Private vs. Protected

• Private members are not available to derived
  classes. You could make itsAge and itsWeight
  public, but that is not desirable. You don't want
  other classes accessing these data members
  directly.
• What you want is a designation that says, "Make
  these visible to this class and to classes that
  derive from this class." That designation is
  protected. Protected data members and functions
  are fully visible to derived classes, but are
  otherwise private.

55
Overriding vs. Overloading functions
56
Overriding Functions

• When do we need to override functions?
• If you are a programmer example in your slides.
• If we consider Woof of the dog as speak
  example.
• When a derived class creates a function with the
  same return type and signature as a member
  function in the base class, but with a new
  implementation, it is said to be overriding that
  method.

57
Overriding example

• include ltiostream.hgt
• enum BREED YORKIE, CAIRN, DANDIE, SHETLAND,
  DOBERMAN, LAB
• class Mammal
• public
• // constructors
• Mammal() cout ltlt "Mammal constructor...\n"
• Mammal() cout ltlt "Mammal destructor...\n"
• //Other methods
• void Speak()const cout ltlt "Mammal sound!\n"
• void Sleep()const cout ltlt "shhh. I'm
  sleeping.\n"
• protected
• int itsAge
• int itsWeight
• class Dog public Mammal
• public
• // Constructors
• Dog() cout ltlt "Dog constructor...\n"

58
Overloading Functions

• When you overload a method, you create more than
  one method with the same name, but with a
  different signature. When you override a method,
  you create a method in a derived class with the
  same name as a method in the base class and the
  same signature.

59
Overloading example

• includeltiostream.hgt
• int area(int x) // square area
• int area(int x,int y) //triangle area
• float area(int x,int y, int radius)
  //circle area
• int main()
• int x4, y5, rad3
• coutltlt"The Square area is "ltltarea(x)
• coutltlt"\nThe Triangle area is "ltltarea(x,y)
• coutltlt"\nThe Circle area is
  "ltltarea(x,y,rad)
• getchar()
• return 0
• int area(int x) // square area
• return xx

Output The Square area is 16 The Triangle area
is 20 The Circle area is 28.26
60
Another overloading example

• include ltiostream.hgt
• class Mammal
• public
• void Move() const cout ltlt "Mammal move one
  step\n"
• void Move(int distance) const
• cout ltlt "Mammal move "
• cout ltlt distance ltlt" _steps.\n"
• protected
• int itsAge
• int itsWeight
• class Dog public Mammal
• public
• // You may receive a warning that you are hiding
  a function!
• void Move() const cout ltlt "Dog move 5
  steps.\n"
• int main()

Output Mammal move one step Mammal move 2
steps. Dog move 5 steps
61
Virtual Functions

• To call a function youve overridden in a derived
  class you need to use virtual functions.
• Example
• struct Base
• virtual void do_something() 0
• struct Derived1 public Base
• void do_something()
• cout ltlt "I'm doing something"
• struct Derived2 public Base
• void do_something()
• cout ltlt "I'm doing something else"
• int main()
• Base pBase new Derived1
• pBase-gtdo_something()//does something
• delete pBase
• pBase new Derived2
• pBase-gtdo_something()//does something else

62
Another Example
int main() Mammal theArray5
Mammal ptr int choice, i for
( i 0 ilt5 i) cout ltlt
"(1)dog (2)cat (3)horse (4)pig " cin
gtgt choice switch (choice)
case 1 ptr new Dog
break case 2 ptr new Cat
break case 3 ptr new
Horse break case 4
ptr new Pig break
default ptr new Mammal break
theArrayi ptr
for (i0ilt5i)
theArrayi-gtSpeak()
system("pause") return 0
includeltstdlib.hgt include ltiostream.hgt
class Mammal public
Mammal()itsAge(1) Mammal()
virtual void Speak() const cout ltlt "Mammal
speak!\n" protected int itsAge
class Dog public Mammal
public void Speak()const cout ltlt
"Woof!\n" class Cat public
Mammal public void Speak()const
cout ltlt "Meow!\n" class Horse
public Mammal public void
Speak()const cout ltlt "Winnie!\n"
class Pig public Mammal public
void Speak()const cout ltlt "Oink!\n"

• Output
• (1)dog (2)cat (3)horse (4)pig 1
• (1)dog (2)cat (3)horse (4)pig 2
• (1)dog (2)cat (3)horse (4)pig 3
• (1)dog (2)cat (3)horse (4)pig 4
• (1)dog (2)cat (3)horse (4)pig 5
• Woof!
• Meow!
• Winnie!
• Oink!
• Mammal speak!

63
Virtual functions, When?

• Only if you have to redefine a function in a
  Derived class that is already defined in Base
  Class, otherwise, its just extra resources when
  executed.

64
Pointers to base class

• include ltiostreamgt
• using namespace std
• class CPolygon
• protected
• int width, height
• public
• void set_values (int a, int b)
• widtha heightb
• class CRectangle public CPolygon
• public
• int area ()
• return (width height)
• class CTriangle public CPolygon
• public

Output 20 10
65
Templates

• Used in place of a specific data type. For
  example, use a template to add data types
  together, whichever data type the user wishes
  (i.e. integers, floats)

66
Function Template
Output 6 10.5

• include ltiostreamgt
• using namespace std
• template ltclass Tgt
• T GetMax (T a, T b)
• T result
• result (agtb)? a b
• return (result)
• int main ()
• int i5, j6, k
• float l10.5, m5.6, n
• kGetMaxltintgt(i,j)
• nGetMaxltfloatgt(l,m)
• cout ltlt k ltlt endl
• cout ltlt n ltlt endl
• getchar()
• return 0

67
Other Template cases

• int i
• long l
• k GetMax (i,l)
• This would not be correct, since our GetMax
  function template expects two arguments of the
  same type.
• But if we did the following
• template ltclass T, class Ugt
• T GetMin (T a, U b)
• return (altb?ab)
• Then we could call the function like this
• int i,j
• long l
• i GetMinltint,longgt (j,l)
• Or simply
• i GetMin (j,l)

68
Class Template

• include ltiostreamgt
• using namespace std
• template ltclass Tgt
• class mypair
• T a, b
• public
• mypair (T first, T second) // constructor
• afirst
• bsecond
• T getmax ()
• template ltclass Tgt
• T mypairltTgtgetmax ()
• T retval
• retval agtb? a b
• return retval
• int main ()
• mypair ltintgt myobject (100, 75)

Output 100
69
Templates cntd.

• mypairltintgt myobject (115, 36)
• This same class would also be used to create an
  object to store any other type
• mypairltdoublegt myfloats (3.0, 2.18)

70
More on Templates

• include ltiostreamgt
• using namespace std
• // class template
• template ltclass Tgt
• class mycontainer
• T element
• public
• mycontainer (T arg) elementarg
• T increase () return element
• // class template specialization
• template ltgt
• class mycontainer ltchargt
• char element
• public
• mycontainer (char arg) elementarg
• char uppercase ()

Output 8 J
71
Errors and Exception Handling

• Always check for points where your program could
  get into undesirable action.
• Programmer should be responsible for adding
  exception handling code to eliminate unexpected
  end of execution.
• assert is a function that checks if an
  expression meets certain conditions.

72
Simple assert example

• include ltstdio.hgt
• include ltassert.hgt
• void print_number(int myInt)
• assert (myInt!NULL) // make sure that a
  value had been assigned to myInt
• printf ("d\n",myInt)
• int main ()
• int a10
• int b NULL
• int c NULL
• ba
• print_number (b)
• print_number (c)
• return 0

73
try/catch Exception handling

• A way of handling Exceptions, example
• include ltiostreamgt
• using namespace std
• int main()
• char buf
• try
• buf new char512
• if( buf 0 )
• throw "Memory allocation failure!"
• catch( char str )
• cout ltlt "Exception raised " ltlt str ltlt
  '\n'

Output Exception raised Memory allocation
failure!
74
try/catch Exception handling

• The catch block is only executed if an error was
  thrown in the try block.
• catch(data type) the data type in this case
  inform us that this catch can catch an exception
  of type integer.
• A catch block with ellipses()catches any type of
  exception.

75
C Exception Classes

• Two classes derived from exception
• Logic_error
• Runtime_error
• Both classes are defined in the stdexcept header
  file.
• invalid_argument class deals with illegal
  arguments in function calls. The class
  out_of_range and length_error are another
  examples.

76
More classes on Exception handling

• bad_alloc when new fail to allocate memory.
• run_time_error errors occurring during
  excexution.
• overflow_error and underflow_error deals with
  arithmetic overflow and underflow both derived
  from run_time_error class.

77
Exception Example
void MyFunc() CDtorDemo D coutltlt "In
MyFunc(). Throwing CTest exception.\n" throw
CTest() int main() cout ltlt "In
main.\n" try cout ltlt "In try block,
calling MyFunc().\n" MyFunc()
catch( CTest E ) cout ltlt "In catch
handler.\n" cout ltlt "Caught CTest
exception type " cout ltlt E.ShowReason()
ltlt "\n" catch( char str )
cout ltlt "Caught some other exception " ltlt str ltlt
"\n" cout ltlt "Back in main. Execution
resumes here.\n" system("pause")

• include ltiostreamgt
• using namespace std
• void MyFunc( void )
• class CTest
• public
• CTest()
• CTest()
• const char ShowReason() const
• return "Exception in CTest class."
• class CDtorDemo
• public
• CDtorDemo()
• CDtorDemo()

78
Output of previous example

• In main. In try block, calling MyFunc().
  Constructing CDtorDemo. In MyFunc(). Throwing
  CTest exception. Destructing CDtorDemo. In catch
  handler. Caught CTest exception type Exception
  in CTest class. Back in main. Execution resumes
  here.

79
Exception Handling Techniques

• Terminate the Program Input files does not
  exist, no meaning of continue
• Include code to recover from exception User
  inputs wrong type, just inform user to re-enter
  correct format.
• Log the error and continue The program should be
  always running no matter what happened (
  Monitoring satellites for example)

80
Recursion

• By recursion we let a function call it self
  recursively until a break condition is met
• The break condition is usually set in the base
  case of the problem
• Example, factorial problem
• 0!1 this is the base case
• n! n(n-1)! If ngt0, this is the general case
• Always general case should reduce o base case

81
Factorial wihout using Recursive

• includeltiostream.hgt
• int main()
• int n5 double fact1
• for(int i1iltni)
• factfacti
• coutltltfact
• getchar()

82
Recursive version of factorial

• includeltiostream.hgt
• double fact(int)
• int main()
• int n5 double factVar1
• factVarfact(n)
• coutltltfactVar
• getchar()
• double fact(int f) // Since the factorial grow
  fast, its better to make it
  // double
• if(f0)return 1
• else return fact(f-1)f

83
Fibonacci sequence example

• The Fibonacci sequence looks like this
• 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233,
  ...
• Fibonacci equations are
• F(1) 1F(2) 1F(n) F(n  1) F(n  2)

84
Fibonacci implementation

• includeltiostream.hgt
• int fib(int) // Fibonacci function prototype
• int main()
• int n10 // The index of Fibonacci that we
  need to get
• coutltltfib(n)
• getchar()
• int fib(int x)
• if(x1 x2) return 1
• else
• return fib(x-1)fib(x-2)

85
Hannoi Tower example

• includeltiostream.hgt
• void hannoiTower(int,int,int,int)
• static int counter0
• int main()
• int disk17
• long beginTime time(NULL) // Record
  starting time
• hannoiTower(disk,1,3,2)
• long endTime time(NULL)// Record Ending
  time
• coutltlt\n Time CPU spent in
  calculatingltltendTime-beginTime
• coutltlt"\nNumber of disk moves were
  "ltltcounter
• getchar()
• return 0

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Hannoi function

• void hannoiTower(int count,int needle1,int
  needle3,int needle2)
• if(countgt0)
• hannoiTower(count-1,1,2,3)
• coutltlt"Move disk "ltltcountltlt" from
  "ltltneedle1
• ltlt" to "ltltneedle3ltlt"."ltltendl
• hannoiTower(count-1,2,3,1)
• counter // To calculate total number
  of disk moves
• // which should
  be 2Number of Disks -1

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Recursion vs. Iterations

• Recursion functions executes more slowly that
  iteration version, and uses more memory and CPU
  time.
• Choosing one method over another depends on the
  nature of the problem
• Iterative method is easier than recursion, so
  unless the problem is inherently recursive, try
  to avoid recursion.

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• Questions??
• Good Luck from REACH in your Test