Difference between call by value and call by reference

The parameters that appear in a function call statement are actual parameter and the parameter in function definition are called formal parameters.
In call by value method a copy of argument values r created and is then used in the function whereas in call by reference method the original variables are used in function call.
example:

1:)Swap numbers by call by value method:

void main()
{
void swap(int,int);
int a,b;
a=7;
b=4;
cout<<"the original values r";
cout<<"a="<<a<<"b="<<b;
swap(a,b);// invoke swap function 2 interchange a and b
cout<<"the values after swap() r";
cout<<"a="<<a<<"b="<<b;
getch();
}
void swap(int x,int y)
{
 int temp;
temp=x;
x=y;
y=temp;
cout<<"swapped values r";
cout<<"a="<<x<<"b="<<y;
}


output will b

a=7 b=4
swapped values r a=4 b=7
the values after swap() r a=7 b=4


2:)  Swap numbers by call by value method:

void main()
{
void swap(int &,int &);
int a,b;
a=7;
b=4;
cout<<"the original values r";
cout<<"a="<<a<<"b="<<b;
swap(a,b);// invoke swap function 2 interchange a and b
cout<<"the values after swap() r";
cout<<"a="<<a<<"b="<<b;
getch();
}
void swap(int &x,int &y)
{
 int temp;
temp=x;
x=y;
y=temp;
cout<<"swapped values r";
cout<<"a="<<x<<"b="<<y;
}


output will b

a=7 b=4
swapped values r a=4 b=7
the values after swap() r a=4 b=7 (i.e. a and b are modified)

Character set

The characters C++ can identify:
Letters: A-Z , a-z
Digits: 0-9
Special symbols: + , - ,  * , / , ^ ,  (  , ) ,  [  , ]  ,{  , } ,= , !=(not in c++ is represented by ! ), <  , > ,' ," $ , : . ; ,  % , @
White spaces Blank spaces , Horizontal tab ,Newline,Form feed.
Other Character : all 256 ASCII characters

Starting with C++

First download the Turbo c setup file.You will get a zip folder .Extract those files and then run the set up file

if you hav a 32 bit O.S. then no need of DOS BOX but in case u hav 64 bit O.S.  download  DOS BOX and write the following commands in it:

mount c c:\

c:\

Cd TC\BIN

TC.EXE

You can also download Borland compiler

DNS

The character based naming system by which servers are identified is known as domain name system(DNS).
Some most common domain names: com, edu, gov, net, org and co .

Web Browser And Web Server

The world wide web is based upon clients and server.
A www client is called Web Browser.
and a www server is called a Web server or just a server.

A web browser is a www client that navigates thru the World wide web and displays web pages .
A web server is WWW server that responds to the requests made by web browsers.