|
Only at PS Code
-
Code of the Day
To join the 'Code
of the Day' Mailing List click
here!
| Thank you for coming to Planetsourcecode |
|
 |
|
Style: In the
first tutorial some people had pointed out that I had not declared main()
to return void, this is no longer a standard expected from programmers.
Get main() to return int & simply return
0; as the last line in main().
|
Note:
According to the latest standards <iostream.h> is
not required it can be simply written as <iostream>,
with the standard code that shall be used through out the
tutorial (I hope!).
If the standard code in the tutorial does not work
on your compiler and you still wish to use <iostream>
instead of <iostream.h> just add a line
using namespace
std;
& if this does not work you have an old
compiler which cannot work with these standards.
|
|
| - Preprocessor
Preprocessing is done when the #include command is
used to add header files. The actual preprocessing is
done much before the compiler reaches the code
section of your program. The #include command is one
of the possible actions of preprocessing.
All Preprocessing is done with #(Hash/Pound Symbol)
- #include
This a directive to the preprocessor, with the help
of the " Include Hash/Pound " the file after
the directive s read.
Eg: #include <filename>
or #include <filename.h> |
| - IO
When generally the topic of input is raised, the
first thought that comes to a person's mind is that
input means input from a keyboard, mouse, joystick,
etc and is outputted to a device such as a disk, monitor
(screen) or printer & this thought is technically
correct; in explaining the concept of input-output.
- Input is done in streams of bytes or a sequence
from devices (e.g.. keyboard, mouse, joystick,
etc).
-In Output bytes flow from the output devices.
A program is divided into bits, bytes, a byte may
represent ASCII characters.
The C++ iostream library has many I/O capabilities
but for now we are only concerned with a few.
The <iostream> header file defines the
cin, cout objects.
|
|
|
|
| I think the theoretical
explanation of the beginning of a program should be
enough for now. Let us now get to the 'real' juicy
part of programming. (Duh - Writing the code)
- 2 Input/Output Objects ( In
relation to the tutorial)
cout (It ain't pronounced as Cowt, its
pronounced as C Out)
The cout operator has already been explained in tutorial
1 but here is a brief review + additions.
cout is a keyword, which is exclusively reserved
for C++ defined purposes. It is used to output data
info to the standard output device.
cout<<"This is Text";
By the way Comments(
// ) have been explained previously.
// << is known as
stream insertion operator.
// "This is Text"
is displayed to the screen.
//The << is also known
as left shift operator, it is used after the cout
command.
cout<<text;
//The data from a variable
text is displayed to the screen.
//Variables have not yet been
explained at this point.
|
|
|
|
|
|
Now to explain the next topic cin & datatype (int), we shall
attempt to understand by studying a simple program. - Adding 2
integers
| Non
Standard Version
#include <iostream>
int main()
{
int one, int two,
int sum;
cout<<"Please enter the first number"; //Requests for first integer
cin>>one; //accepts first integer
cout<<"Please enter the second number"; //Requests for second integer
cin>>two; //accepts second integer.
sum = one + two; // one & two get added and the value gets assigned to sum.
cout<<"The sum:"<<sum; //sum of 2 int's is displayed
return 0; //program has ended
} |
|
| Standard
Version
#include <iostream>
using std::cout;
using std::cin;
int main()
{
int one, int two,
int sum;
cout<<"Please enter the first number"; //Requests for first integer
cin>>one; //accepts first integer
cout<<"Please enter the second number"; //Requests for second integer
cin>>two; //accepts second integer.
sum = one + two; // one & two get added and the value gets assigned to sum.
cout<<"The sum:"<<sum; //sum of 2 int's is displayed
return 0; //program has ended
}
|
|
|
|
|
|
|
|
|
