Midterm1 Review

1
Midterm1 Review

• Dr. Hairong Zhao
• hairong_at_calumet.purdue.edu
• Purdue University Calumet

2
Midterm 2

• Wednesday, Feb 22
• 1230-150pm
• This room
• Format
• true or false
• fill in blank
• multiple choice
• programming
• Topics chapter 1 6, exclude ADT

3
Computer Organization

• Input devices
• Output devices
• Processor (CPU)
• Memory
• Main memory
• Memory locations containing the running program
• Address number that identifies a memory location
• Bit and Byte
• A digit that can only be zero or one
• Each memory location has eight bits
• RAM Computer can directly access any memory
  location
• Secondary memory
• Permanent record of data often on a disk

4
C High-level Languages

• C
• a high-level language
• derived from C
• object oriented
• Compiler
• Translate source code into object code
• Linker combines all the object codeinto an
  executable program

5
Program Errors

• Syntax errors
• Violation of the grammar rules of the language
• Discovered by the compiler
• Error messages may not always show correct
  location of errors
• Run-time errors
• Error conditions detected by the computer at
  run-time
• Logic errors
• Errors in the programs algorithm
• Most difficult to diagnose
• Computer does not recognize an error

6
Variables

• Type int, float, char, structure, class
• Value, address
• Names (identifiers)
• First character must be
• a letter or the underscore character
• Remaining characters must be
• Letters, numbers, or underscore character
• Can not be keywords (reserve words)
• Before use, variables must be declared
• Variables are initialized in assignment
  statements double mpg // declare the
  variable mpg 26.3 // initialize
  the variable

7
Input and output

• Stream a sequence of data
• cin extraction operator gtgt
• cin skips blanks and line breaks
• cout insertion operator ltlt
• What is wrong with the following statements?
• cin ltlt number
• cout gtgt endl
• Include Directives add library files to our
  programs include ltiostreamgt
• Using Directives include a collection of defined
  names using namespace std
• Include Directives and Using Directives do not
  have to be used togeter

8
Data Types

• int 34 45 1 89
• Other integer type long or long int, short or
  short int
• double
• 34.1 23.0034 1.0 89.9
• 3.41e1 means 34.1
• Other double type long double, float
• char
• What is the difference of a and a?
• Hom many haracters can file_name contain?
• char file_name16
• bool

15
9
Data Types

• Escape sequences
• \n -- new line
• \t -- a tab \\ -- a
  backslash character \" -- a quote
  character
• What is the difference of \n and \n?
• Formatting Real Numbers
• setf(iosfixed)
• setf(iosshowpoint)
• precision(2)
• setf(iosshowpos)

10
Type compatibility

• int ?? double
• Variables of type double should not be assigned
  to variables of type int
• Integer values can normally be stored in
  variables of type double
• char ? ? int not recommend
• int value 'A' char letter 65
• bool ? ? int not recommend

11
Operators

• / and
• 5/3, 53, 5/3.0 51.0/3
• static_castltdoublegt(5)/3
• 5/static_castltdoublegt(3)
• static_castltdoublegt(5/3)
• -- /
• Result of an operator
• int x3, y 4
• double z 4.0
• What is xy? What is xz?

12
Simple Flow of Control

• gt lt ! equal or equivalent
• !
• (2 lt x) (x lt 7) !( x lt 2) (2 lt x)
  (x lt 7)
• ( 2 lt y lt 7 )
• If statement
• Does if always paired with else? No
• What is the output
• x1
• if(x1)
• cout ltlt x1 ltlt endl
• cout ltlt x!1 ltlt endl
• What is the output
• x2
• if(x1)
• cout ltlt x1 ltlt endl
• else
• cout ltlt x!1 ltlt endl

x1 x!1
Always true
x1
13
loop

• While
• Show the output of this code if x is of type
  int?x 10while ( x gt 0) cout ltlt x
  ltlt endl x x 3
• What about this
• x 0
• while (x ! 12)
• cout ltlt x ltlt endl
• x x 2
• A do-while loop is always executed at least once

10 7 4 1
Infinite loop
14
Function

• Function header, body, declaration, definition?
• Function declaration 2 ways
• List formal parameter names
• List types of formal parameters, but not names
• A function can only return one value, but it can
  have many return statements.
• A function call must be preceded by either
• The functions declaration or
• The functions definition
• If the functions definition precedes the call,
  a declaration is not needed
• In function call, the parameters and arguments
  are matched by there relative positions in the
  parameter lists.

15
Function

• Call-by-value, call-by-reference
• Call-by-reference parameters allow us to
  changethe variable used in the function call
• Arguments for call-by-reference parameters must
  bevariables, not numbers
• Call-by-value and call-by-reference parameters
  can be mixed in the same function
• symbol (ampersand) identifies as a
  call-by-reference parameter
• Used in both declaration and definition, but not
  in the function call
• Void function
• No return value
• can still have return statement

16
Overloading function

• Overloading a function providing more than one
  declaration and definition using the same
  function name
• Overloaded functions must have
• different numbers of formal parameters OR
• at least one different type of parameter

17
Predefined Functions

• Predefined function in cmath
• sqrt(4.0), pow(2.0, 3), floor(6.99), ceil(1.01)
• Must use
• include ltcmathgt
• using namespace std

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Functions with Default Arguments

• A default value can be specified in the parameter
  list
• The default value is selected if no argument is
  available for the parameter
• void default_args(int arg1, int arg2 -3)
  cout ltlt arg1 ltlt ' ' ltlt arg2 ltlt endl
• default_args can be called with one or two
  parameters
• default_args(5) //output is 5 -3
• default_args(5, 6) //output is 5 6

19
Functions and name space

• Different functions can have different name
  spaces
• Using directives can be placed
• Outside any function
• At the beginning of a function definition

20
Using Constants

• What is wrong with the following
• const double PI 3.14159
• PI3.14
• Local variables variables declared in a
  function have the function as their scope and
  they cannot be used from outside the function
• Global Named Constant
• Declared outside any function body including main
• Declared before any function that uses it

21
File input/output

• Declare a file stream
• ifstream in_stream // input-file stream
  variable ofstream out_stream // output-file
  stream variable
• You must use
• include ltfstreamgtusing namespace std
• Connecting a stream to a file
• in_stream.open("infile.dat")
• out_stream.open("outfile.dat")
• Using the streams
• in_stream gtgt one_number gtgt another_number
• out_stream ltlt "one number " ltlt
  one_number ltlt "another number
  " ltlt another_number

22
File input/output

• Disconnecting a stream from a file
• in_stream.close()
• out_stream.close()
• To append new output to the end an existing file
• outStream.open("important.txt", iosapp)
• If the file does not exist, a new file will be
  created
• fail and exit in_stream.open("stuff.dat")
  if( in_stream.fail( ) ) cout ltlt
  "Input file opening failed.\n" exit(1)
  
• // include ltcstdlibgt should be used
  for exit

23
File input/output

• A manipulator is a function that is used after
  the insertion operator (ltlt)
• cout ltlt "Start" ltlt setw(4) ltlt 10 ltlt setw(6) ltlt
  30
• cout.setf(iosfixed)
• cout.setf(iosshowpoint)
• cout ltlt "" ltlt setprecision(2) ltlt 10.3 ltlt
  endl ltlt "" ltlt 20.5 ltlt endl
• To use these manipulators, add include
  ltiomanipgt using namespace std
• endl is a manipulator defined in ltiostreamgt

24
File input/output

• Boolean expression (in_stream gtgt next)
• Streams can be arguments to a function
• The function's formal parameter for the stream
  must be call-by-reference
• Function get
• Member function of every input stream
• Reads one character from an input stream
• Does not skip blanks

25
File input/output

• Function put
• Member function of every output stream
• Requires one argument of type char
• Places its argument of type char in the output
  stream
• Member function eof detects the end of a file
• if ( ! in_stream.eof( ) )

26
Inheritance and Streams

• cin object of the class istream (no 'f ')
• Input-file streams are objects of the class
  ifstream, which is derived from istream.So
  input-file streams are also objects of istream
• cout object of class ostream
• Output-file streams are objects of class
  ofstream, which is derived from ostream
• The following function can be called with
  ostream or ofstream arguments void
  say_hello(ostream any_out_stream)
  any_out_stream ltlt "Hello"

27
Character Functions

• Several predefined functions
• toUpper, toLower, isspace
• The cctype library is required
• include ltcctypegtusing namespace std

28
Structure

• Define a structure
• struct CDAccount double
  balance double interest_rate int term
  //months to maturity
• Member of structure are public by default
• To declare two variables
• CDAccount my_account, your_account
• A structure can be initialized
• CDAccount my_account 100, 10, 10

29
Structure

• Use the dot operator to access
• member variable my_account.balance
• member variable of hierarchical Structure
• cout ltlt person1.birthday.year
• Structures can be arguments in function calls
• The formal parameter can be call-by-value
• The formal parameter can be call-by-reference
• Structures can be the type of a value returned
  bya function
• The assignment operator can be used to
  assignvalues to structure types

30
Class

• Define a class
• Class className
• public
• // member functions private // member
  variables
• // member functions
• A member function can be public or private
• Objects of the same class have
• same member functions
• different member variables

31
Member function

• Define use to identify a member void
  DayOfYearoutput( )
  // function body
• scope operator
• Call use . to identify a member
  birthday.output( )
• Call a public function from outside must include
  the object name
• Call a private function can only be from another
  member function, object name is not used

32
The Assignment Operator

• Objects and structures can be assigned values
  with the assignment operator ()

33
Constructors

• A constructor
• used to initialize member variables when an
  object is declared
• Usually public
• automatically called when an object of the class
  is declared
• BankAccount account1
• account1.BankAccount(10, 50, 2.0)
• must be the same name as the class
• cannot return a value
• can be overloaded
• default constructor no parameters
  BankAccount account1 // uses the default
  BankAccount constructor BankAccount account1()
  // illegal

34
Initialization Sections

• An initialization section in a function
  definitionprovides an alternative way to
  initialize member variables
• BankAccountBankAccount( ) balance(0),
  interest_rate(0.0)
• // No code needed in this example
• The values in parenthesis are the initial values
  for the member variables listed

35
Programming

• Using if else, and while loop
• Define a structure
• Define a class, write member functions
• Constructor
• Accessor, mutator
• Output member variables to file or cout
• Other functions