1. C++ 프로그래밍 Introduction to this class & C++
1/9/2018
C++ 프로그래밍 Introduction to this class & C++
Howon Kim

2. About this course… Course name : C++ Programming (CP24106)
Objective of this class:
Obtaining the basic ideas of object‑oriented programming
Understanding C++ as a tool for problem solving
Exercising computer programming to a practical level
Understanding the basic concepts of software engineering
Understanding the basic concepts of data structures

3. About this course… About me… Current Major Interests
Howon Kim, Ph.D. from POSTECH, Feb. 1999
Joined to PNU from this semester
Phone: ,
Current Major Interests
Public Key Cryptography (especially, ECC and Pairing)
Low power consumed cryptographic techniques (RFID security, sensor network security)
Sensor network security issues (TinyOS security, secure routing etc.)
Cryptanalysis (with side channel attack)
Teaching the CP24106 class !

4. About this course… Prerequisite class Textbook References Class time
C Programming
(미수강 전문과정 학생  선수과목 test 필요)
Textbook
Walter Savitch, Absolute C++, 3rd Ed., Addison Wesley, 2008
References
Bjarne Stroustrup, The C++ Programming Languages, 3rd Ed., Addison Wesley
Liang, Introduction to C++, Prentice Hall, 2007
Class time
Tuesday, Thursday, 13:00 ~ 14:00

5. About this course… Detailed schedule on this class 범위 학습내용 주
C++ Basics 1
CH 2
Flow of Control 2
CH 3
Function Basics 3
CH 4
Parameters and Overloading 4
CH 5
Arrays 5
CH 6
Structures and Classes 6
CH 7
Constructors and Other Tools 7
Midterm Exam 8
CH 8
Operator Overloading , Friends, and Refrences 9
CH 12
Stream Input and Output 10
CH 14
Inheritance and OOP 11
CH 16
Templates
CH 18
Exception Handling
CH 19
STL(Standard Template Library) 14
Final Exam 15
Term project 수행

6. About this course… Assessment 점 수 항 목 5 출 석 40 중간고사 기말고사 15 과제물 100
합 계

7. What Is C and What Is C++?
The C language was developed originally by Bell Laboratories and standardized by the American National Standards Institute (ANSI) in 1989.
In 1990 the International Standards Organization (ISO) adopted the ANSI standard.
C was expanded to include the ability to build object-oriented software, and hence named C++ in the mid 1990s.
In short, C++ contains all of the C language features and more!

8. A Brief History of C and C++
In the early 1970s at the Bell Laboratories, C was used originally as a programming language for operating systems, including Bell Labs’ UNIX.
For many years the C software supplied with the UNIX operating system was the standard.
As C grew in popularity and computer hardware became more affordable, many versions of the C language were created.
In 1982 an American National Standards Institute committee was formed to create the ANSI standard for the C language.

9. A Brief History of C and C++
This standard was adopted in 1989 and ensured that developers of C software used the same rules and procedures.
In 1994 extensions and corrections to the ISO C standard were adopted.
Extensions to the C language, providing an improved version of C as well as supporting object-oriented programming methodologies, were designed originally by Bjarne Stroustrup of AT&T Bell Labs.
These extensions to the C language became known as the C++ language.

10. A Brief History of C and C++
In November 1997, after several drafts of the ISO C++ standards, the ANSI committee published the final draft of the language - making it an international standard.

11. How C Was Named
To appreciate how C was named, one needs to examine the historical aspects of the language.
C is the result of a development process that began in the early 1960s with ALGOL 60, then Cambridge’s CPL in 1963, Martin Richard’s BCPL in 1967, and Ken Thompson’s B language in 1970 at Bell Labs.
Many of C’s principal concepts are based in BCPL, and these concepts influenced the B and C languages.

12. C/C++ Is a Compiled Language
Create source code. Source code contains the actual lines of C or C++ statements that give the program direction.
Compile the program. A compiler is a computer program that reads the source code, and if the code is “grammatically correct,” the compiler produces machine code
The next build step uses a linker, which literally links, or hooks, the machine code and library code together and binds it into an executable file.
A C++ program must be compiled and linked on its target machine because the C++ executable file “talks” to the processor directly. Note the changes that must be made.

13. Creating, Compiling, and Running Programs

14. Rules for Programmers Keep you cool (don’t get mad).
Work when you are rested (don’t program when you are tired).
KISS your software (keep it simple, sweetie).
Give help/get help.
Study and know the rules for the language (syntax).

15. Rules for Programmers
Learn the development environment and tools (we’ll concentrate on Visual C++).
Understand the problem you are trying to solve.
Build and test your software in steps.
Save early/save often (back up your computer programming files often).

16. Why Programmers Love C++
Extended set of data “containers”
Numeric: both whole numbers and numbers with decimal precision
Character: text values
True/false data type bool in C++
Pointers and References
Variables that “point” or “refer” to other variables

17. Why Programmers Love C++
Large number of operators
Operators are symbols that perform certain actions in C++.
The + symbol adds numbers, - subtracts.
The * multiplies numbers.
Basic decision and control structures enable a program to branch to different code statements or loop over statements.
C++ uses functions.
A function is a block of code that performs a task for the program.

18. Why Programmers Love C++
Functions allow the programmer to:
organize code and separate tasks logically
separate each piece of the program in its own function and place all the functions in a separate library
keep the program size from becoming too large and unwieldy

19. Why Programmers Love C++
Integrated libraries provide useful functions and classes for mathematics, file input/output, text operations, and other tools.
Standard Template Library which contains software utilities that are built and ready for use by the C++ programmer.
The C++ language provides us many classes, and we can write our own classes as well.

20. Object-Oriented Programming - OOP
In the old days, programs followed data flow, written line-by-line, and “flowed” from the top to the bottom step by step. This is called structured (or top-down) programming.
In OOP, the program is based on real-world things (objects) - designed and built to model how these “real” things interact.
A C++ program is not automatically object-oriented. For a program to be object-oriented, it must contain objects.

21. Introduction to C++ C++ Origins C++ Terminology Low-level languages
Machine, assembly
High-level languages
C, C++, ADA, COBOL, FORTRAN
Object-Oriented-Programming in C++
C++ Terminology
Programs and functions
Basic Input/Output (I/O) with cin and cout
From these slides, I will use the materials form Pearson.
Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 21

22. Display 1.1 A Sample C++ Program (1 of 2)22

23. Display 1.1 A Sample C++ Program (2 of 2)23

24. C++ Variables C++ Identifiers Variables
Keywords/reserved words vs. Identifiers
Case-sensitivity and validity of identifiers
Meaningful names!
Variables
A memory location to store data for a program
Must declare all data before use in program

25. Data Types: Display 1.2 Simple Types (1 of 2)

26. Data Types: Display 1.2 Simple Types (2 of 2)

27. Assigning Data Initializing data in declaration statement
Results "undefined" if you don’t!
int myValue = 0;
Assigning data during execution
Lvalues (left-side) & Rvalues (right-side)
Lvalues must be variables
Rvalues can be any expression
Example: distance = rate * time; Lvalue: "distance" Rvalue: "rate * time"

28. Assigning Data: Shorthand Notations
Display, page 14

29. Data Assignment Rules Compatibility of Data Assignments
Type mismatches
General Rule: Cannot place value of one type into variable of another type
intVar = 2.99; // 2 is assigned to intVar!
Only integer part "fits", so that’s all that goes
Called "implicit" or "automatic type conversion"
Literals
2, 5.75, "Z", "Hello World"
Considered "constants": can’t change in program

30. Literal Data Literals Cannot change values during execution
Examples:
2 // Literal constant int
5.75 // Literal constant double
"Z" // Literal constant char
"Hello World" // Literal constant string
Cannot change values during execution
Called "literals" because you "literally typed" them in your program!

31. Escape Sequences "Extend" character set
Backslash, \ preceding a character
Instructs compiler: a special "escape character" is coming
Following character treated as "escape sequence char"
Display 1.3 next slide

32. Display 1.3 Some Escape Sequences (1 of 2)

33. Display 1.3 Some Escape Sequences (2 of 2)

34. Constants Naming your constants Use named constants instead
Literal constants are "OK", but provide little meaning
e.g., seeing 24 in a pgm, tells nothing about what it represents
Use named constants instead
Meaningful name to represent data const int NUMBER_OF_STUDENTS = 24;
Called a "declared constant" or "named constant"
Now use it’s name wherever needed in program
Added benefit: changes to value result in one fix

35. Arithmetic Operators: Display 1.4 Named Constant (1 of 2)
Standard Arithmetic Operators
Precedence rules – standard rules

36. Arithmetic Operators: Display 1.4 Named Constant (2 of 2)

37. Arithmetic Precision Precision of Calculations
VERY important consideration!
Expressions in C++ might not evaluate as you’d "expect"!
"Highest-order operand" determines type of arithmetic "precision" performed
Common pitfall!

38. Arithmetic Precision Examples
17 / 5 evaluates to 3 in C++!
Both operands are integers
Integer division is performed!
17.0 / 5 equals 3.4 in C++!
Highest-order operand is "double type"
Double "precision" division is performed!
int intVar1 =1, intVar2=2; intVar1 / intVar2;
Performs integer division!
Result: 0!

39. Individual Arithmetic Precision
Calculations done "one-by-one"
1 / 2 / 3.0 / 4 performs 3 separate divisions.
First 1 / 2 equals 0
Then 0 / 3.0 equals 0.0
Then 0.0 / 4 equals 0.0!
So not necessarily sufficient to change just "one operand" in a large expression
Must keep in mind all individual calculations that will be performed during evaluation!

40. Type Casting Casting for Variables
Can add ".0" to literals to force precision arithmetic, but what about variables?
We can’t use "myInt.0"!
static_cast<double>intVar
Explicitly "casts" or "converts" intVar to double type
Result of conversion is then used
Example expression: doubleVar = static_cast<double>intVar1 / intVar2;
Casting forces double-precision division to take place among two integer variables!

41. Type Casting Two types Implicit—also called "Automatic"
Done FOR you, automatically 17 / 5.5 This expression causes an "implicit type cast" to take place, casting the 17  17.0
Explicit type conversion
Programmer specifies conversion with cast operator (double)17 / 5.5 Same expression as above, using explicit cast (double)myInt / myDouble More typical use; cast operator on variable

42. Shorthand Operators Increment & Decrement Operators
Just short-hand notation
Increment operator, ++ intVar++; is equivalent to intVar = intVar + 1;
Decrement operator, -- intVar--; is equivalent to intVar = intVar – 1;

43. Shorthand Operators: Two Options
Post-Increment intVar++
Uses current value of variable, THEN increments it
Pre-Increment ++intVar
Increments variable first, THEN uses new value
"Use" is defined as whatever "context" variable is currently in
No difference if "alone" in statement: intVar++; and ++intVar;  identical result

44. Post-Increment in Action
Post-Increment in Expressions: int n = 2, valueProduced; valueProduced = 2 * (n++); cout << valueProduced << endl; cout << n << endl;
This code segment produces the output: 4 3
Since post-increment was used

45. Pre-Increment in Action
Now using Pre-increment: int n = 2, valueProduced; valueProduced = 2 * (++n); cout << valueProduced << endl; cout << n << endl;
This code segment produces the output: 6 3
Because pre-increment was used

46. Console Input/Output I/O objects cin, cout, cerr
Defined in the C++ library called <iostream>
Must have these lines (called pre- processor directives) near start of file:
#include <iostream> using namespace std;
Tells C++ to use appropriate library so we can use the I/O objects cin, cout, cerr

47. Console Output What can be outputted?
Any data can be outputted to display screen
Variables
Constants
Literals
Expressions (which can include all of above)
cout << numberOfGames << " games played."; 2 values are outputted: "value" of variable numberOfGames, literal string " games played."
Cascading: multiple values in one cout

48. Separating Lines of Output
New lines in output
Recall: "\n" is escape sequence for the char "newline"
A second method: object endl
Examples:
cout << "Hello World\n";
Sends string "Hello World" to display, & escape sequence "\n", skipping to next line
cout << "Hello World" << endl;
Same result as above

49. Formatting Output Formatting numeric values for output
Values may not display as you’d expect! cout << "The price is $" << price << endl;
If price (declared double) has value 78.5, you might get:
The price is $ or:
The price is $78.5
We must explicitly tell C++ how to output numbers in our programs!

50. Formatting Numbers
"Magic Formula" to force decimal sizes: cout.setf(ios::fixed); cout.setf(ios::showpoint); cout.precision(2);
These stmts force all future cout’ed values:
To have exactly two digits after the decimal place
Example: cout << "The price is $" << price << endl;
Now results in the following: The price is $78.50
Can modify precision "as you go" as well!

51. Error Output Output with cerr Re-direct output streams
cerr works same as cout
Provides mechanism for distinguishing between regular output and error output
Re-direct output streams
Most systems allow cout and cerr to be "redirected" to other devices
e.g., line printer, output file, error console, etc.

52. Input Using cin cin for input, cout for output Differences:
">>" (extraction operator) points opposite
Think of it as "pointing toward where the data goes"
Object name "cin" used instead of "cout"
No literals allowed for cin
Must input "to a variable"
cin >> num;
Waits on-screen for keyboard entry
Value entered at keyboard is "assigned" to num

53. Prompting for Input: cin and cout
Always "prompt" user for input cout << "Enter number of dragons: "; cin >> numOfDragons;
Note no "\n" in cout. Prompt "waits" on same line for keyboard input as follows:
Enter number of dragons: ____
Underscore above denotes where keyboard entry is made
Every cin should have cout prompt
Maximizes user-friendly input/output

54. Program Style Bottom-line: Make programs easy to read and modify
Comments, two methods:
// Two slashes indicate entire line is to be ignored
/*Delimiters indicates everything between is ignored*/
Both methods commonly used
Identifier naming
ALL_CAPS for constants
lowerToUpper for variables
Most important: MEANINGFUL NAMES!

55. Libraries C++ Standard Libraries #include <Library_Name>
Directive to "add" contents of library file to your program
Called "preprocessor directive"
Executes before compiler, and simply "copies" library file into your program file
C++ has many libraries
Input/output, math, strings, etc.

56. Namespaces Namespaces defined: For now: interested in namespace "std"
Collection of name definitions
For now: interested in namespace "std"
Has all standard library definitions we need
Examples: #include <iostream> using namespace std;
Includes entire standard library of name definitions
#include <iostream>using std::cin; using std::cout;
Can specify just the objects we want

57. Summary 1 C++ is case-sensitive Use meaningful names
For variables and constants
Variables must be declared before use
Should also be initialized
Use care in numeric manipulation
Precision, parentheses, order of operations
#include C++ libraries as needed

58. Summary 2 Object cout Object cin Object cerr
Used for console output
Object cin
Used for console input
Object cerr
Used for error messages
Use comments to aid understanding of your program
Do not overcomment

59. Q&A
Thank you for your attention.
Thank you. 59

60. Reference
[1] Walter Savitch, Absolute C++, 3rd Ed., Addison Wesley, 2008
[2] Liang, Introduction to C++, Prentice Hall, 2007
[3] Barbara Johnston, C++ Programming Today, 2nd Ed., Prentice Hall, 2007