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geishaannealagos

This document provides an overview of programming in C++ using Turbo C++. It covers the Turbo C++ integrated development environment, basic C++ program structure, modular programming using functions, control structures like if/else statements, and problem solving approaches. Examples are provided for calculating areas and volumes, temperature conversions, and other mathematical problems. Function prototypes, call by value vs reference, and selection structures like switch statements are also discussed. The document aims to teach basic C++ concepts and skills like breaking problems into modular functions.

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1 Programming in C++ The Turbo C++ Environment C++ Program Structure Modular Programming with Functions C++ Control Structures Advanced Data Types Classes
2 Turbo C++ Environment Windows based product  Integrated Development Environment (IDE) – editor – compiler – linker – debugger
3 Structure of a C++ Program preprocessor directives main function header { declare statements statements }
4 Using the Turbo C++ IDE  tool bars menu editor
5 Using the Turbo C++ IDE (2) compiling  linking executing
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 Developing Programs (2) Verify – Test and debug the solution » using test cases from design phase Maintain
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 Problem Solving -- Trapezoid Pseudocode input b1 input b2 input height bases = b1 + b2 area = bases * h /2 output area
10 Problem Solving (2) consider finding the area and circumference of a circle pi = 3.14159 area = pi * radius2 circumference = 2 * pi * radius
11 Problem Solving -- Circle Functions Pseudocode pi = 3.14159 input radius circum = 2 * pi * radius area = pi * radius * radius output area output circum
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 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 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 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 Problem Solving -- Commission Pseudocode Multiple Salespeople quota = 15 input number_salespeople
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 Exercise -- GO Develop a series of problems for the students to do using each of the statement types
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 Preprocessor Statements library header files -- #include < > -- system library #include <iostream.h> “ “ -- personal library #include “apstring.h”
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 User Defined Data Types  class -- mechanism to establish new data types ap classes – string » apstring.h apstring.ccp – bool » bool.h
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 Input and Output Statements #include <iostream.h> cout -- output << insertion character cin -- input >> extraction character
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 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 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 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 Assignment Statements assignment operator = – operator precedence and mixed mode arithmetic hold combination operators +=, -=, *=, /=, %= variable = expression;
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 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 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 Mathematical Functions (math.h) code reuse  sqrt, pow, exp, log, log10 abs, ceil, floor  trigonometric functions
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 Programming Problems (2) determine the distance from a point on the Cartesian plane to the origin – distance = sqrt (x2 + y2)
36 Exercise -- GO Implement the sequential problems developed in the first exercise
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 Modular Programming with Functions (2) allows for reuse eliminates redundancy allows for team development  simplifies logic
39 Form of a Function [return data type] Function name (parameter list) { [declarations] statements [return ] }
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 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 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
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 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 Example Call by Value (2) main test n i n i 1 6 1 6 5
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 Reversing Order -- Swap if (num1 < num2) { temp = num1; num1 = num2; num2 = num1; }
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 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 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 Exercise modify circle.cpp to use reference where appropriate modify pyth.cpp to have compute_sides
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 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 Exercise -- GO Implement all previous programs using modular design and reference and value parameters as appropriate
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 Overloading function names can be overloaded – different interfaces – compiler can determine which to execute operators can be overloaded as well
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 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 Selection -- IF ELSE  if (condition) statement; else statement;  if (condition) { statements; } else {statements; }
60 If ELSE -- Examples  if (x>y) max = x; else max = y;
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 Programming Example  find the reciprocal of an integer undefined for 0 – attempt to divide by 0 will cause program termination  recip.cpp
63 Programming Exercise Modify the program which finds the roots of the quadratic equation so that it will not error terminate – quad.cpp
64 Logical Operators combine two or more relational operators to create complex relations AND -- && OR -- || NOT -- ! precedence && before ||
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 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 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 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 BREAK statement allows program to leave a control structure form -- break;
70 Multiple Selection -- Switch  test the value of a single integer type and perform different blocks of statements based upon the value
71 Multiple Selection -- Switch Form switch (expression) { case value 1: statement(s); break; case value 2: statement (s); break; .... [default: statement(s); break;]}
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 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 Example Programming Problem color compliments clswitch.cpp
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 Exercise -- GO Implement the selection statement problem solving problems
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 While Loop form while (condition) { statement(s); } event driven loop
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 Example While Loop i = 5; while (i > 0) { cout << i << endl; i--; }
81 Programming Example taking averages enter values to be averaged until sentinel is entered (0) – event which terminates loop ave.cpp
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 Do While Loop event driven loop always executes at least once (1 loop) post test loop form do{ statement(s); }while (condition);
84 Do While Loop (2) executes the loop  tests the condition – if true executes the loop again – if false exits the loop
85 Do While Example add the numbers from 1 to 5 sum = 0; i = 1; do{ sum += i; i ++; }while (i <= 5);
86 Programming Example  display square of input value user prompt to continue squares.cpp
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 Programming Exercise -- Pythagorean Triples robust example – m > n and both > 0 give meaningful error message
89 For Loop counted loop -- set number of times  iterates through a set of values for (initial expression; condition; loop expression) { statement(s); }
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 Example For Loop - I Countdown for (i = 1; i<=5; ++i) { cout << i << endl; }
92 Example For Loop - II sum numbers 1-5 for (sum = 0, i = 1; i <= 5; ++i) { sum += i; }
93 Programming Examples  Factorials – fact.cpp – change fact to be integer (see what happens) temperature conversions – temps.cpp generating random numbers – random.cpp
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 Programming Exercise maintain check book balance modular $15 service fee for bad check – display message  final balance on exit
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 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*/
99 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
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 Lines in Cartesian Plane perpendicular, parallel or intersecting slope enumeration type can be used – parameters – return types  lines.cpp
103 Exercise -- GO Implement any remaining problem solving programs. Be sure have a complete set identifying all structures including enumeration types.
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 ArraysVectors  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]
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 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 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
112 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
114 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;
119 ArraysVectors  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];
123 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();

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Apclass (2)

  • 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 m>n 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 (x>y) 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 – 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. 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” 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. 121 Declaring Vectors (2) apvector<apstring> (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 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. 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. 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 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. 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 apmatrix<int> 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;r<imat.numrows();r++) for (c=0;c<imat.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();