C++ L01-Variables

C++
L01 -VARIABLES
Programming Language
Mohammad Shaker
mohammadshaker.com
@ZGTRShaker
2010, 11, 12, 13, 14

Resources
•Books
–Deitel–C++ How to program
–The C++ Programming Language (Not for complete starters)
•Bunshof good websites
–www.cplusplus.com
–www.msdn.com
•msdnawesome library
•stackoverflow.comand googleare always your best programming buddies

What You Will Learn
•Concepts you already know
–Variables
–Control Structure
–Functions
–Arrays/ Pointers/ Strings
–Structs
•New concepts
–Classes (OOP)
–Inheritance (OOP)
–Polymorphism (OOP)
–Template
–STL
–Exception Handling
–File Processing

Programming Languages War
August 2014, Source: http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html

C++ Preferences & features
•Moore’s Law
–Computer processing power can be doubled every 18-24 months
–Software with Hardware improves together
•More complicated Hardware
•More advanced Software
–Now, we are in generation that we put the "Moore’s Law" behind us!

C++ Preferences & features
•Two kind of Computer programming paradigms:
–Imperative
•Procedural(Pascal, C, php, etc)
•Object-Oriented(C++, C#, Java, ASP.NET, etc)
–Declarative
•Functional(Pascal, C, php, etc)
•Logic(Prolog, etc)
____________________________________________________________________________
* Note the need to C++ after inventing C
** Note that the Procedural Functional programming paradigms are still used till our present time and has its unique features

C C++
•The "C" Programming language is a modular one
•Why C++ then?
–Objects, OOP
–C C++ are portables ones
•Comparison:
–C: is action Oriented
•Procedural
–C++: is object oriented
•Compiler checking
•Extensible language
–Class
•Reusable

Where you can find C++? Pretty Everywhere! (Take a look here: http://www.stroustrup.com/applications.html) Microsoft, OfficeGoogleHPAmazonAdobeMozillaMySQLINTELNokiaSunBloombergGame Engines

Enough talk! Let’s get into the Action!

The Structure of a C++ Program

Structure of C++ program
#include<iostream>
voidmain ()
{
}
#include<iostream>
intmain ()
{
// indicate successful termination
return0;
}
#include<iostream>
usingnamespace::std; // Note the new namespace
voidmain()
{
cout<< "we're having fun!";
}
#include<iostream>
usingnamespace::std;// Note the new namespace
intmain ()
{
cout<< "we're having fun!";
return0; // indicate successful termination
}

#include<iostream>
usingnamespace::std; // Note the namespace
voidmain()
{cout<< "we're having fun!";}
#include<iostream>
usingnamespace::std;// Note the namespace
intmain ()
{
cout<< "we're having fun!";return0;
}
#include<iostream>
usingnamespace::std;
voidmain()
{
cout<< "We're having fun!";
cout<< "I need to eat!:D ";
}
#include<iostream>
voidmain()
{
cout<< "we're having fun!" << endl;
cout<< "I need to eat!:D " << endl;
}
We're having fun!Ineed to eat!:D
we're having fun!
I need to eat!:D

#include<iostream>
voidmain()
{
cout<< "we're having fun!"<< "n"<< "I need to eat!:D "
<< "n";
}
#include<iostream>
voidmain()
{
cout<< "we're having fun! n I need to eat!:D n";
}
we're having fun!
I need to eat!:D
we're having fun!
I need to eat!:D nis the same as endl

Comments
// comment
For a one line
/*
comments
*/
For one line or more (multi lines)

#include<iostream>
voidmain()
{
cout<< "foo"; // this is a line!
}
#include<iostream>
voidmain()
{
cout<< "foo"; /* this is a line! */
}
Compile and run
Compile and run

#include<iostream>
voidmain()
{
cout<< "foo"; // this is
a line!
}
#include<iostream>
voidmain()
{
cout<< "foo"; /* this is not a single
line! */
}
Compiler error
Compile and run

I/O Stream
•Keyboard / Screen
Keyboard
input stream
Executing program
screen
Output
stream

float, double, long double
C++ data types
Structured
Simple
Address
Pointer
Reference
enum
Floating
Array
Struct
Union
Class
Char, Short, int, long, bool
Integral

Variables
•Every variable has:
–Name
–Type
–Size
–Value
•Data Types:
–Integer, Double, float, char

Variables
#include<iostream>
voidmain()
{
inti;
float j;
}
#include<iostream>
voidmain()
{
inti;
intj;
}
Compile and Run
Compile and Run
#include<iostream>
voidmain()
{
inti, j;
}
Compile and Run

Variables
#include<iostream>
voidmain()
{
inti, j;
i= 0;
j = 4;
}
#include<iostream>
voidmain()
{
inti= 0, j = 4;
}
Compile and Run
Compile and Run

Variables
#include <iostream>
using namespace::std;
void main()
{
inti;
cin>> i;
cout<< " i= " << I;
}
#include<iostream>
voidmain()
{
intI;
cout<< I;
}
Compiler error, undeclared "I" identifier
C++ is case sensitive
Runtime Error –Visual 2010
Variable must be initialized

Variables
#include<iostream>
voidmain()
{
inti, j;
cin>> i>> j;
intsum = i+ j;
cout<< sum;
}
#include<iostream>
voidmain()
{
inti, j;
cin>> i>> j;
intsum = i+ j;
cout<< “ sum = ” << sum;
}

Variables
// Operating with variables
#include <iostream>
usingnamespacestd;
intmain ()
{
// declaring variables:
inta, b;
intresult;
// process:
a = 5; b = 2; a = a + 1;
result = a -b;
// print out the result:
cout<< result;
// terminate the program:
return0;
}

Variables
#include<iostream>
usingnamespacestd;
voidmain()
{
inti= 0;
i= i+ 1;
cout<< i;
}
#include<iostream>
usingnamespacestd;
voidmain()
{
inti= 0;
i+= 1;
cout<< i;
}
1
1
#include<iostream>
usingnamespacestd;
voidmain()
{
inti= 0;
i++;
cout<< i;
}
1

Variables
#include<iostream>
usingnamespacestd;
voidmain()
{
inti= 0;
i--;
cout<< i;
}
#include<iostream>
usingnamespacestd;
voidmain()
{
inti, j;
i++;
j--;
cout<< i<< j;
}
-1
Runtime Error –Visual Studio 2010

Variables
#include<iostream>
voidmain()
{
inti, j;
cin>> i;
cout<< endl;
cout<< "i= "<< i<< endl<< "t";
cin>> j;
cout<< "j = n"<< j;
cout<< "______________________________"<< endl;
cout<< "j+i= "<< j+i<< "n";
cout<< "2*i= "<< 2*i<< "n";
}
2
i= 2
3
j =
3______________________________
j+i= 5
2*i= 4
Press any key to continue

Float, double, long double
C++ data types
Structured
Simple
Address
Pointer
Reference
enum
Floating
Array
Struct
Union
Class
Char, Short, int, long, bool
Integral

Integral
•char, short, int, long, bool
•char
–Used to represent character such as:
•Letters
•Digits
•Special symbols
–' + ', ' & ', ' $ ', ' * '
–Each character is enclosed with single quote mark ' ' and not double ones " "
–Space is represented by ' ' with space between them.
–ASCII & EBCDIC
•bool
–Watch out that the "Boolean" type is an integral one!
–bool
•false = 0, true = any other number

integral
#include<iostream>
voidmain()
{
charc1 = 'd', c2;
cout<< c2 << c1 << endl;
}
voidmain()
{
boolb1, b2;
if(3 <= 2)
{
b1 = false;
b2 = true;
}
else
{
b1 = 53;
}
cout<< b1 << " -"<< b2 << endl;
}
d
1 -0
Note that:
•The default value for a char is NULLrepresented as SPACE‘ ’ but it’s not a space, it’s a NULL!
•The char has ' ' and not " "
Note that:
•A numeric value is printed when printing a "boolean"
•The default value for booltype is false (0)

Floating point data types
•float, double
–float 4 bytes / double 8 bytes
•float has a single precision
•double has a double precision
–double = long double (in new compilers)
–The size of float, double, long double are machine dependent.

integral
#include<iostream>
voidmain()
{
doubled=0.4;
cout<<d<<endl;
system("pause");
}
#include<iostream>
voidmain()
{
doubled=0.0;
cout<<d<<endl;
system("pause");
}
0.4
0
#include<iostream>
voidmain()
{
doubled=.0;
cout<<d<<endl;
system("pause");
}
#include<iostream>
voidmain()
{
doubled=0.0;
cout<<d<<endl;
system("pause");
}
0
0

integral
#include<iostream>
voidmain()
{
floatf=1.2;
cout<<f<<endl;
system("pause");
}
#include<iostream>
voidmain()
{
floatf=1.2f;
cout<<f<<endl;
system("pause");
}
1.2
1.2

Constants
•A Constant:
–Any expression that has a “fixed” value
•3 kind of constants:
•Integer Numbers
•Floating-Point Numbers
•Characters & Strings

Constants
•Integer Numbers
–1225// Decimal
–-982// Decimal
–05356// Octal!
•Octal numbers are preceded by 0
–0x3c// Hexadecimal
•Hexadecimal numbers are preceded by 0x
•Floating Numbers
–Decimal
–Exponent
Examples:
–5.0// 5.0 (double)
–5.0f// 5.0 (float)
–45.556779// 45.556779
–8.36e18// 8.36x 10^18
–8.36e-18// 8.36x 10^-18
•Characters and Strings
–'Z' //Char –Single Character
–'M' //Char –Single Character
–"Where’s the cat?"//String – Several Character
–"I just don’t know!"//String – Several Character
–“c” //String –One Character

integral
#include<iostream>
#definePI 3.14;// No “=” Sign
#defineMyTab't‘// No “=” Sign
#definePonPon":D“// No “=” Sign
voidmain()
{
}
#include<iostream>
voidmain()
{
#definePI 3.14;
#defineMyTab't'
#definePonPon":D“
}

integral
#include<iostream>
#defineMyTab't'
voidmain()
{
#definePI 3.14;
floatRadius = 0;
cout<< "Enter the Radius"<< endl;
cin>> Radius;
floatCircle = PI;
Circle = Circle * 2 * Radius;
cout<< "The perimeter of the Circle = “<< Circle
<< MyTab;
}
Enter the Radius
3.2
The perimeter of the Circle = 20.096 Press any key to continue

integral
#include <iostream>
using namespace::std;
#define MyTab't'
#define PI 5;
void main()
{
#define PI 3.14;
float Radius = 0;
cout<< "Enter the Radius" << endl;
cin>> Radius;
float Circle = PI;
Circle = Circle * 2 * Radius;
cout<< "The perimeter of the Circle = “<< Circle
<< MyTab;
}
Enter the Radius
3.2
The perimeter of the Circle = 20.096 Press any key to continue

integral
#include<iostream>
voidmain()
{
#definePI 3.14;
floatRadius = 0;
cout<< "Enter the Radius"<< endl;
cin>> Radius;
floatCircle = 2 * PI * Radius;
cout<< "The perimeter of the Circle = "<< Circle;
}
Illegal Indirection 2 * PI * Radius

integral
#include<iostream>
constintx = 20;
voidmain()
{
constinty = 90;
}
Compile and run
#include<iostream>
constintx = 20;
voidmain()
{
consty = 90;
}
2005 Compiler: Compile & Run
intassumed for consttype when neglecting the type
constcharMe = 'M';
constintHeight = 5;
constcharMyCharTab= 't';// Char tab
constchar*MyStringTab= "t"; // String tab
voidmain()
{
cout<< MyStringTab;
}
constcharMyCharTab= 't';// Char tab
constchar*MyStringTab= "t";// String tab
#defineMyStringTab"t"; // String tab
voidmain()
{
cout<< MyStringTab;
}

Code Cracking
#include<iostream>
voidmain()
{
cout<<"I'm number 4 or 77, I don't know :D"<<endl;
;
;
;
;
system("pause");
}
I'm number 4 or 77, I don't know :D

Related Online CoursesProgramming ParadigmsC++ Memory Management. LISP and Pythonhttp://see.stanford.edu/see/courseinfo.aspx?coll=2d712634-2bf1-4b55-9a3a-ca9d470755eeProgramming methodology -Javahttp://see.stanford.edu/see/courseinfo.aspx?coll=824a47e1-135f-4508-a5aa-866adcae1111

Take a look at my other courses, Especially the GUI Course, C++.NEThttp://www.slideshare.net/ZGTRZGTR/

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Hope you have enjoyed your first class

C++ L01-Variables

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C++ L01-Variables