1. By Dr. Awad Khalil Computer Science & Engineering Department
Overview of C++ By
Dr. Awad Khalil
Computer Science & Engineering Department

2. CSCI 106, Overview of C++, by Dr. Awad Khalil
C++ Language Elements
Comments make a program easier to understand
// Used to signify a comment on a single line
/* Text text */ use if comments on multi lines
Don’t embed comments within /* */ comments
CSCI 106, Overview of C++, by Dr. Awad Khalil

3. CSCI 106, Overview of C++, by Dr. Awad Khalil
Compiler Directives
#include
Compiler directive
Processed at compilation time
Instructs compiler on what you want in the program
#include <iostream>
Adds library files to program
Used with < >
Also “ “ user defined
CSCI 106, Overview of C++, by Dr. Awad Khalil

4. CSCI 106, Overview of C++, by Dr. Awad Khalil
Compiler Directives
Stream data type
Object that is a stream of characters
Defined in iostream
Entered on the keyboard (cin)
Displayed on monitor (cout)
CSCI 106, Overview of C++, by Dr. Awad Khalil

5. CSCI 106, Overview of C++, by Dr. Awad Khalil
Declarations
Direct compiler on requirements
Based on data needs (data identifiers)
Each identifier needed must be declared
Comma used to separate identifiers
cin and cout are undeclared identifiers
Special elements called streams
cin - input stream , cout - output stream
Included with the iostream not declared
CSCI 106, Overview of C++, by Dr. Awad Khalil

6. Executable Statements
cout get output
cout << “Enter the fabric size in square meters: ”;
cin get input
cin >> sizeInSqmeters;
Assignment
sizeInSqyards = metersToYards * izeInSqmeters;
CSCI 106, Overview of C++, by Dr. Awad Khalil

7. Reserved Words and Identifiers
Reserved words have special meanings
Can NOT be used for other purposes (const, float and void are some examples)
Identifiers (variables)
Used to store data by the program (user defined)
Valid identifiers - letter, letter1, _letter
Invalid identifiers - 1letter, const, hell o
Special symbols
C++ has rules for special symbols
= * ; { } ( ) // << >>
CSCI 106, Overview of C++, by Dr. Awad Khalil

8. CSCI 106, Overview of C++, by Dr. Awad Khalil
Upper and Lower Case
C++ case sensitive
Compiler differentiates upper & lower case
Identifiers can be either
Be careful though (cost != Cost)
Blank spaces
Use space to make program readable
Use care in placing spaces
CSCI 106, Overview of C++, by Dr. Awad Khalil

9. User-Defined Identifier
An Identifier must always begin with a letter or underscore symbol (not recommended)
An identifier must consist of letters, digits, or underscore only.
You cannot use a C++ reserved word as an identifier.
CSCI 106, Overview of C++, by Dr. Awad Khalil

10. User-Defined Identifier
Invalid Identifiers
1Letter
Float
Const
Two*Four
Joe’s
Two-dimensional
CSCI 106, Overview of C++, by Dr. Awad Khalil

11. Data Types and Declarations
Predefined data types
int (integers)
Positive or negative whole numbers
INT_MAX - largest int allowed by compiler
float (real numbers)
Positive or negative decimal numbers
bool (boolean)
true
false
char (Characters)
Represent characters
CSCI 106, Overview of C++, by Dr. Awad Khalil

12. CSCI 106, Overview of C++, by Dr. Awad Khalil
Data Type: int
The basic integer type is int
The size of an int depends on the machine and the compiler
On pc’s it is normally 16 or 32 bits
Other integers types
short: typically uses less bits
long: typically uses more bits
Different types allow programmers to use resources more efficiently
Standard arithmetic and relational operations are available for these types
CSCI 106, Overview of C++, by Dr. Awad Khalil

13. CSCI 106, Overview of C++, by Dr. Awad Khalil
Data Type: float
Floating-point types represent real numbers
Integer part
Fractional part
The number breaks down into the following parts
integer part
fractional part
C++ provides three floating-point types
float
double
long double
CSCI 106, Overview of C++, by Dr. Awad Khalil

14. CSCI 106, Overview of C++, by Dr. Awad Khalil
Data Type: char
char (characters)
Individual character value (letter or number)
Character literal enclosed in single quotes ‘A’
Character type char is related to the integer types
Characters are encoded using a scheme where an integer represents a particular character
CSCI 106, Overview of C++, by Dr. Awad Khalil

15. Character Encoding Schemes
ASCII is the dominant encoding scheme
Examples
' ' encoded as 32
'+' encoded as 43
'A' encoded as 65
'Z' encoded as 90
’a' encoded as 97
’z' encoded as 122
CSCI 106, Overview of C++, by Dr. Awad Khalil

16. Character Encoding Schemes
UNICODE
CSCI 106, Overview of C++, by Dr. Awad Khalil

17. CSCI 106, Overview of C++, by Dr. Awad Khalil
string Class
String object data type
A literal string constant is a sequence of zero or more characters enclosed in double quotes
"Are you aware?\n"
Individual characters of string are stored in consecutive memory locations
The null character ('\0') is appended to strings so that the compiler knows where in memory strings ends
CSCI 106, Overview of C++, by Dr. Awad Khalil

18. CSCI 106, Overview of C++, by Dr. Awad Khalil
string Class
String literal
“A”
“1234”
“Enter the distance”
Additional data types included in library
#include <string>
Various operations on strings
CSCI 106, Overview of C++, by Dr. Awad Khalil

19. CSCI 106, Overview of C++, by Dr. Awad Khalil
Declarations
Identifiers should be
Short enough to be reasonable to type (single word is norm)
Standard abbreviations are fine (but only standard abbreviations)
Long enough to be understandable
When using multiple word identifiers capitalize the first letter of each word
Examples
char response;
int minelement;
float score;
float temperature;
int i;
int n;
char c;
float x;
CSCI 106, Overview of C++, by Dr. Awad Khalil

20. Constant Declarations
Types of constants
integer
float
char
bool
string objects
Associate meaningful terms
const float PAYRATE = 10.25;
CSCI 106, Overview of C++, by Dr. Awad Khalil

21. CSCI 106, Overview of C++, by Dr. Awad Khalil
Hello.cpp
// FILE: Hello.cpp
// DISPLAYS A USER'S NAME
#include <iostream>
#include <string>
using namespace std;
int main () {
char letter1, letter2;
string lastName;
// Enter letters and print message.
cout << "Enter 2 initials and last name: ";
cin >> letter1 >> letter2 >> lastName;
cout << "Hello " << letter1 << ". " <<
letter2 << ". " << lastName << "! ";
cout << "We hope you enjoy studying C++." << endl;
return 0; }
CSCI 106, Overview of C++, by Dr. Awad Khalil

22. Executable Statements
Memory status
Before and after
Assignments
Form: result = expression;
sizeInSqyards = metersToYards * sizeInMeters;
sum = sum + item;
CSCI 106, Overview of C++, by Dr. Awad Khalil

23. CSCI 106, Overview of C++, by Dr. Awad Khalil
Arithmetic Operators
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulus
CSCI 106, Overview of C++, by Dr. Awad Khalil

24. Input / Output Operations
#include <iostream> library
cin >> sizeInSqmeters;
Output
cout << squareArea;
CSCI 106, Overview of C++, by Dr. Awad Khalil

25. CSCI 106, Overview of C++, by Dr. Awad Khalil
Program Input: cin
Form: cin >> dataVariable;
cin >> age >> firstInitial;
Extracted from cin (input stream)
>> Directs input to variable
cin associated with keyboard input (stdin)
Used with int, float, char, bool and strings
Leading blanks ignored (floats, int, char,bool and strings)
Char read 1 at a time (1 non blank)
Case issues
int or float will read until space
Stings same as int and float
CSCI 106, Overview of C++, by Dr. Awad Khalil

26. CSCI 106, Overview of C++, by Dr. Awad Khalil
Program Output: cout
Form: cout << dataVariable;
cout << squareArea;
Output stream cout
<< Output operator (insertion operator)
cout << “my height in inches is: “ << height;
Blank lines
endl; or “\n”;
CSCI 106, Overview of C++, by Dr. Awad Khalil

27. General Form of a C++ Program
General program form
Function basic unit (collection of related statements)
A C++ program must contain a main function
void main ()
int - function returns integer value
main - lower case with ()
{ } - Braces define the function body
CSCI 106, Overview of C++, by Dr. Awad Khalil

28. General Form of a C++ Program
General form of function body parts
Declaration statements
Variables and constants
Executable statements
C++ statements
CSCI 106, Overview of C++, by Dr. Awad Khalil

29. General Form of a C++ Program
// File: filename
// Program description:
#include directives
int main() {
Declarations section
Executable statements section }
CSCI 106, Overview of C++, by Dr. Awad Khalil

30. Arithmetic Expressions
int data type
+ - * /, Assignment, input and output on int
% Only used with int
Examples of integer division
15 / 3 = 5
15 / 2 = 7
0 / 15 = 0
15 / 0 undefined
CSCI 106, Overview of C++, by Dr. Awad Khalil

31. CSCI 106, Overview of C++, by Dr. Awad Khalil
Modulus and Integer
Used only with integer and yields remainder
Examples of integer modulus
7 % 2 = 1
299 % 100 = 99
49 % 5 = 4
15 % 0 undefined
CSCI 106, Overview of C++, by Dr. Awad Khalil

32. Mixed-type Assignments
Expression evaluated
Result stored in the variable on the left side
C++ can mix types
float a, b, x;
int m, n;
a=10;
b=5;
x = m / n;
CSCI 106, Overview of C++, by Dr. Awad Khalil

33. Expressions With Multiple Operators
Operator precedence tells how to evaluate expressions
Standard precedence order
() Evaluated first, if nested innermost done first
* / % Evaluated second. If there are several, then evaluate from left-to-right
+ - Evaluate third. If there are several, then evaluate from left-to-right
CSCI 106, Overview of C++, by Dr. Awad Khalil

34. Mathematical Formulas in C++
a = bc not valid C++ syntax
* Operator a = b * c;
m = y - b
x - a
( ) And / m = (y - b) / (x - a);
CSCI 106, Overview of C++, by Dr. Awad Khalil

35. Example 1: Milesbatch.cpp
// File: milesBatch.cpp
// Converts distance in miles to kilometers.
#include <iostream>
using namespace std;
int main() // start of main function {
const float KM_PER_MILE = 1.609;
float miles,
kms;
CSCI 106, Overview of C++, by Dr. Awad Khalil

36. CSCI 106, Overview of C++, by Dr. Awad Khalil
Milesbatch.cpp
// Get the distance in miles.
cin >> miles;
cout << "The distance in miles is " <<
miles << endl;
// Convert the distance to kilometers.
kms = KM_PER_MILE * miles;
// Display the distance in kilometers.
cout << "The distance in kilometers is " <<
kms << endl;
return 0; }
CSCI 106, Overview of C++, by Dr. Awad Khalil

37. CSCI 106, Overview of C++, by Dr. Awad Khalil
Milesbatch.cpp
Program output
The distance in miles is 10
The distance in kilometers is 16.09
CSCI 106, Overview of C++, by Dr. Awad Khalil

38. Example 2: Coin Collection Case Study
Problem statement
Saving nickels and pennies and want to exchange these coins at the bank so need to know the value of coins in dollars and cents.
Analysis
Count of nickels and pennies in total
Determine total value
Use integer division to get dollar value
/ 100
CSCI 106, Overview of C++, by Dr. Awad Khalil

39. Coin Collection Case Study
Analysis (cont)
Use modulus % to get cents value
% 100
Design
Prompt for name
Get count of nickels and pennies
Compute total value
Calculate dollars and cents
Display results
CSCI 106, Overview of C++, by Dr. Awad Khalil

40. Coin Collection Case Study
Implementation
Write C++ code of design
Verify correct data types needed
Mixed mode types and promotion
Testing
Test results using various input combinations
CSCI 106, Overview of C++, by Dr. Awad Khalil

41. CSCI 106, Overview of C++, by Dr. Awad Khalil
Coins.cpp
// File: coins.cpp
// Determines the value of a coin collection
#include <iostream>
#include <string>
using namespace std;
int main() {
// Local data ...
string name;
int pennies;
int nickels;
int dollars;
int change;
int totalCents;
// Prompt sister for name.
cout << "Enter your first name: ";
cin >> name;
CSCI 106, Overview of C++, by Dr. Awad Khalil

42. CSCI 106, Overview of C++, by Dr. Awad Khalil
Coins.cpp
// Read in the count of nickels and pennies.
cout << "Enter the number of nickels: ";
cin >> nickels;
cout << "Enter the number of pennies: ";
cin >> pennies;
// Compute the total value in cents.
totalCents = 5 * nickels + pennies;
// Find the value in dollars and change.
dollars = totalCents / 100;
change = totalCents % 100;
// Display the value in dollars and change.
cout << "Good work " << name << '!' << endl;
cout << "Your collection is worth " <<
dollars << " dollars and " <<
change << " cents." << endl;
return 0; }
CSCI 106, Overview of C++, by Dr. Awad Khalil

43. CSCI 106, Overview of C++, by Dr. Awad Khalil
Coins.cpp
Program output
Enter your first name and press return: Sally
Enter number of nickels and press return: 30
Enter number of pennies and press return: 77
Good work sally!
Your collection is worth 2 dollars and 27 cents.
CSCI 106, Overview of C++, by Dr. Awad Khalil

44. Interactive Mode, Batch and Data Files
Two modes interactive or batch
Keyboard input interactive
Batch mode data provided prior to start
File as input
Input / output redirection
Direct input to program use ‘<‘ symbol
Direct output to a file use ‘>‘ symbol
CSCI 106, Overview of C++, by Dr. Awad Khalil

45. Input / Output Redirection
Program name < datafile
Metric < mydata
Program name > outFile
Metric > outFile
Input and output redirection
Metric < inFile > outFile
CSCI 106, Overview of C++, by Dr. Awad Khalil

46. Common Programming Errors
Syntax
Programs rarely compile
Something always goes wrong
Systematic solutions
Compiler not descriptive
Look at line number before and after error
Watch missing ; and }
Run-time errors
Illegal operation (divide by 0)
Logic errors
Program functions differently than you expect
CSCI 106, Overview of C++, by Dr. Awad Khalil