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Transcript of C++ Programming, Namiq Sultan1 Chapter 2 Introduction to C++ Namiq Sultan University of Duhok...
C++ Programming, Namiq Sultan 1
Chapter 2Introduction to C++
Namiq Sultan
University of Duhok
Department of Electrical and Computer Engineerin
Reference: Starting Out with C++, Tony Gaddis, 2nd Ed.
C++ Programming, Namiq Sultan 2
2.1 The Parts of a C++ Program
• C++ programs have parts and components that serve specific purposes.
C++ Programming, Namiq Sultan 3
Program 2-1
//A simple C++ program
#include <iostream>
using namespace std;
int main ()
{
cout<< “Programming is great fun!”;
return 0;
}
Program Output:
Programming is great fun!
C++ Programming, Namiq Sultan 4
Table 2-1 Special CharactersCharacter Name Description // double slash Marks the beginning of a comment. # Pound sign Marks the beginning of a preprocessor
directive < > Opening and
closing brackets
Encloses a filename when used with the #include directive
( ) Opening and closing parenthesis
Used in naming a function, as in int main ()
{ } Opening and closing braces
Encloses a group of statements, such as the contents of a function.
" " Opening and closing quotation marks
Encloses a string of characters, such as a message that is to be printed on the screen
; Semicolon Marks the end of a complete programming statement
C++ Programming, Namiq Sultan 5
2.2 The cout Object
• Use the cout object to display information on the computer’s screen.
The cout object is referred to as the standard output object.
Its job is to output information using the standard output device
C++ Programming, Namiq Sultan 6
Program 2-2
// A simple C++ program
#include <iostream>
using namespace std;
int main ()
{
cout << “Programming is “ << “great fun!”;
return 0;
}
Output:
Programming is great fun!
C++ Programming, Namiq Sultan 7
Program 2-3
// A simple C++ program#include <iostream>using namespace std;int main (){cout<< “Programming is “;cout << “ great fun!”;return 0;
}
Output: Programming is great fun!
C++ Programming, Namiq Sultan 8
Program 2-4
// An unruly printing program
#include <iostream>
using namespace std;
int main()
{
cout << "The following items were top sellers";
cout << "during the month of June:";
cout << "Computer games";
cout << "Coffee";
cout << "Aspirin";
return 0;
}
Program Output
The following items were top sellersduring the month ofJune:Computer gamesCoffeeAspirin
C++ Programming, Namiq Sultan 9
New lines
• cout does not produce a newline at the end of a statement
• To produce a newline, use either the stream manipulator endl• or the escape sequence \n
C++ Programming, Namiq Sultan 10
Program 2-5
// A well-adjusted printing program
#include <iostream>
using namespace std;
int main()
{
cout << "The following items were top sellers" << endl;
cout << "during the month of June:" << endl;
cout << "Computer games" << endl;
cout << "Coffee" << endl;
cout << "Aspirin" << endl;
return 0;
}
C++ Programming, Namiq Sultan 11
Program Output
The following items were top sellers
during the month of June:
Computer games
CoffeeAspirin
C++ Programming, Namiq Sultan 12
Program 2-6
// Another well-adjusted printing program
#include <iostream>
using namespace std;
int main()
{
cout << "The following items were top sellers" << endl;
cout << "during the month of June:" << endl;
cout << "Computer games" << endl << "Coffee";
cout << endl << "Aspirin" << endl;
return 0;
}
C++ Programming, Namiq Sultan 13
Program Output
The following items were top sellers
during the month of June:
Computer games
Coffee
Aspirin
C++ Programming, Namiq Sultan 14
Program 2-7
// Yet another well-adjusted printing program
#include <iostream>
using namespace std;
int main()
{
cout << "The following items were top sellers\n";
cout << "during the month of June:\n";
cout << "Computer games\nCoffee";
cout << "\nAspirin\n";
return 0;
}
C++ Programming, Namiq Sultan 15
Program Output
The following items were top sellers
during the month of June:
Computer games
Coffee
Aspirin
C++ Programming, Namiq Sultan 16
Table 2-2Table 2-2 Common Escape Sequences Escape Sequence
Name Description
\n Newline Causes the cursor to go to the next line for subsequent printing
\t Horizontal tab
Causes the cursor to skip over to the next tab stop
\a Alarm Causes the computer to beep
\b Backspace Causes the cursor to back up, or move left one position
\r Return Causes the cursor to go to the beginning of the current line, not the next line.
\\ Backslash Causes a backslash to be printed
\' Single quote Causes a single quotation mark to be printed
\" Double quote Causes a double quotation mark to be printed
C++ Programming, Namiq Sultan 17
2.3 The #include Directive
• The #include directive causes the contents of another file to be inserted into the program
• Preprocessor directives are not C++ statements and do not require semicolons at the end
C++ Programming, Namiq Sultan 18
2.4 Variables and Constants
• Variables represent storage locations in the computer’s memory. Constants are data items whose values do not change while the program is running.
• Every variable must have a declaration.
C++ Programming, Namiq Sultan 19
Program 2-8
#include <iostream>using namespace std;int main(){ int value; value = 5; cout << “The value is “ << value << endl;
return 0;}
Program Output:The value is 5
C++ Programming, Namiq Sultan 20
Assignment statements:
Value = 5; //This line is an assignment statement.
• The assignment statement evaluates the expression on the right of the equal sign then stores it into the variable named on the left of the equal sign
• The data type of the variable was in integer, so the data type of the expression on the right should evaluate to an integer as well.
C++ Programming, Namiq Sultan 21
Constants
• A variable is called a “variable” because its value may be changed. A constant, on the other hand, is a data item whose value does not change during the program’s execution.
C++ Programming, Namiq Sultan 22
2.5 Identifiers
• Must not be a keyword
• The first character must be a letter or an underscore
• The remaining may be letters, digits, or underscores
• Upper and lower case letters are distinct
C++ Programming, Namiq Sultan 23
Table 2-3 The C++ Keywords
Asm auto bool break case catch
char class const const_cast continue default
delete do double dynamic_cast else enum
explicit export extern false float for
friend goto if inline int long
mutable namespace new operator private
protected
public register reinterpret_cast return short signed
sizeof static static_cast struct switch template
this throw true try typedef typeid
Type name union unsigned using virtual
void volatile wchar_t while
C++ Programming, Namiq Sultan 24
Table 2-4 Some Variable Names
Variable Name Legal or Illegal?
dayOfWeek Legal
3dGraph Illegal. Cannot begin with a digit.
_employee_num Legal
june1997 Legal
Mixture#3 Illegal. Cannot use # symbol.
C++ Programming, Namiq Sultan 25
2.6 Integer Data Types
• There are many different types of data. Variables are classified according to their data type, which determines the kind of information that may be stored in them.
• Integer variables only hold whole numbers.
C++ Programming, Namiq Sultan 26
Program 2-12
// This program shows three variables declared on the same line.
#include <iostream>using namespace std;
int main()
{
int floors, rooms, suites;
floors = 15;
rooms = 300;
suites = 30;
cout << "The Grande Hotel has " << floors << " floors\n";
cout << "with " << rooms << " rooms and " << suites;
cout << " suites.\n";
return 0;
}
C++ Programming, Namiq Sultan 27
Program Output
The Grande Hotel has 15 floors
with 300 rooms and 30 suites.
C++ Programming, Namiq Sultan 28
2.7 The char Data Type
• Usually 1 byte long
• Internally stored as an integer
• ASCII character set shows integer representation for each character
• ‘A’ == 65, ‘B’ == 66, ‘C’ == 67, etc.
• Single quotes denote a character, double quotes denote a string
C++ Programming, Namiq Sultan 29
Program 2-14
// This program uses character constants
#include <iostream>
using namespace std;
int main()
{
char letter;
letter = 'A';
cout << letter << endl;
letter = 'B';
cout << letter << endl;
return 0;
}
C++ Programming, Namiq Sultan 30
Program Output
A
B
C++ Programming, Namiq Sultan 31
Strings
• Strings are consecutive sequences of characters and can occupy several bytes of memory.
• Strings always have a null terminator at the end. This marks the end of the string.
• Escape sequences are always stored internally as a single character.
C++ Programming, Namiq Sultan 32
• Let’s look at an example of how a string is stored in memory.
• "Sebastian" would be stored.
• ‘A’ is stored as
• “A” is stored as
S e b a ts \0i a n
65
065
C++ Programming, Namiq Sultan 33
Review key points regarding characters, and strings:
• Printable characters are internally represented by numeric codes. Most computers use ASCII codes for this purpose.
• Characters occupy a single byte of memory.
• Strings are consecutive sequences of characters and can occupy several bytes of memory.
• Strings always have a null terminator at the end. This marks the end of the string.
• Character constants are always enclosed in single quotation marks.
• String constants are always enclosed in double quotation marks.
• Escape sequences are always stored internally as a single character.
C++ Programming, Namiq Sultan 34
2.8 Floating Point Data Types
• Floating point data types are used to declare variables that can hold real numbers
C++ Programming, Namiq Sultan 35
// This program uses floating point data types
#include <iostream>using namespace std;
int main()
{
float distance;
float mass;
distance = 1.495979;
mass = 1.989;
cout << "The Distance is " << distance << " kilometers \n";
cout << "The mass is " << mass << " kilograms.\n";
return 0;
}
C++ Programming, Namiq Sultan 36
Program Output
The Sun is 1.4959 kilometers
The mass is 1.989 kilograms.
C++ Programming, Namiq Sultan 37
2.9 The bool Data Type
• Boolean variables are set to either true or false
C++ Programming, Namiq Sultan 38
Program 2-17
#include <iostream>
using namespace std;
int main ()
{
bool boolValue;
boolValue = true;
cout << boolValue << endl;
boolValue = false;
cout << boolValue << endl;
return 0;
}
C++ Programming, Namiq Sultan 39
Program Output
1
0
Internally, true is represented as the number 1 and false is represented by the number 0.
C++ Programming, Namiq Sultan 40
2.11 Variable Assignment and Initialization
• An assignment operation assigns, or copies, a value into a variable. When a value is assigned to a variable as part of the variable’s declaration, it is called an initialization.
C++ Programming, Namiq Sultan 41
Program 2-19
#include <iostream>using namespace std;
int main ()
{
int month = 2, days = 28;
cout << “Month “ << month << “ has “ << days << “ days.\n”;
return 0;
}
Program output:
Month 2 has 28 days.
C++ Programming, Namiq Sultan 42
2.13 Arithmetic Operators
• There are many operators for manipulating numeric values and performing arithmetic operations.
• Generally, there are 3 types of operators: unary, binary, and ternary.
Unary operators operate on one operand Binary operators require two operands Ternary operators need three operands ( ?: in ch 4)
C++ Programming, Namiq Sultan 43
Table 2-8
Table 2-8 Fundamental Arithmetic Operaotrs Operator Meaning Type Example
+ Addition Binary Total = Cost + Tax;
- Subtraction Binary Cost = Total - Tax;
* Multiplication Binary Tax = Cost * Rate;
/ Division Binary SalePrice = Original/2;
% Modulus Binary Remainder = Value%3;
C++ Programming, Namiq Sultan 44
Program 2-21
// This program calculates hourly wages. The variables are used as follows:// regWages: holds the calculated regular wages.// basePay: holds the base pay rate.// regHours: holds the number of hours worked less overtime.// otWages: holds the calculated overtime wages.// otPay: holds the payrate for overtime hours.// otHours: holds the number of overtime hours worked.// totalWages: holds the total wages.
#include <iostream>using namespace std;int main(){
float regWages, basePay = 18.25, regHours = 40.0;float otWages, otPay = 27.78, otHours = 10;float totalWages;
C++ Programming, Namiq Sultan 45
Program 2-21
regWages = basePay * regHours;
otWages = otPay * otHours;
totalWages = regWages + otWages;
cout << "Wages for this week are $" << totalWages << endl;
return 0;
}
C++ Programming, Namiq Sultan 46
2.14 Comments
• Comments are notes of explanation that document lines or sections of a program.
• Comments are part of a program, but the compiler ignores them. They are intended for people who may be reading the source code.
• Commenting the C++ Way
//
• Commenting the C Way
/* */
C++ Programming, Namiq Sultan 47
Program 2-22
// PROGRAM: PAYROLL.CPP
// Written by Herbert Dorfmann
// This program calculates company payroll
#include <iostream>using namespace std;
int main(void)
{
float payRate; // holds the hourly pay rate
float hours; // holds the hours worked
int empNum; // holds the employee number
(The remainder of this program is left out.)
C++ Programming, Namiq Sultan 48
Program 2-24
/* PROGRAM: PAYROLL.CPP
Written by Herbert Dorfmann
This program calculates company payroll */
#include <iostream>using namespace std;
int main(void)
{
float payRate; /* payRate holds hourly pay rate */
float hours; /* hours holds hours worked */
int empNum; /* empNum holds employee number */
(The remainder of this program is left out.)
C++ Programming, Namiq Sultan 49
2.15 Programming Style
• Program style refers to the way a programmer uses identifiers, spaces, tabs, blank lines, and punctuation characters to visually arrange a program’s source code.
Generally, C++ ignores white space. Indent inside a set of braces. Include a blank line after variable declarations.
C++ Programming, Namiq Sultan 50
Program 2-26
#include <iostream>
using namespace std;
int main( ){float shares=220.0; float avgPrice=14.67; cout <<"There
were "<<shares<<" shares sold at $"<<avgPrice<<" per share.\
n";return 0;}
Program Output
There were 220 shares sold at $14.67 per share.
C++ Programming, Namiq Sultan 51
Program 2-27
// This example is much more readable than Program 2-26.
#include <iostream>using namespace std;
int main(void)
{
float shares = 220.0;
float avgPrice = 14.67;
cout << "There were " << shares << " shares sold at $";
cout << avgPrice << " per share.\n";
return 0;
}
Program Output
There were 220.0 shares sold at $14.67 per share.