Tutorial 3

				

 

Tutorial
 3- By: Amin Patel  
 
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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().

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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.
 
 
 
 


 
 <-- Begin Search Code -->

 

    Now Pay attention, with a
little explanation and review of the first tutorial
we shall proceed. Some people requested for the
theoretical details.
 

 
 

- 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

}

 


 



 

 

 


 
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_______________________________________________________________________
  If you like this code please
give me a good message.  If you have gained some
knowledge from this tutorial please make me happy, by giving
me an “excellent rating”. That's all I ask.
_______________________________________________________________________
 Tutorial 3 - By: Amin Patel
 


 

 

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