EDITORS
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STUDY OF EDITORS AND TYPES OF EDITORS
Editor is a system
program that interfaces a program with the entity that generates a data
(originator). It also interfaces the results of the program with the entity
that consumes them (consumer).There are a few steps in program development:
1)
program design, coding and documentation
2)
preparation of programs in machine
readable form
3)
program translation, linking and coding
4)
program testing an d debugging
5)
performance enhancement of the program
6)
reforming the data or the result of the program
ü Design
and Coding:
There are two methods
for design and coding:
ü Program Generator:
It generates a program which performs a set
of functions described in its specifications. The user has to only specify the
functions to be performed and not how to perform them.
ü Program Environment:
It supports programming by including
awareness of the programming language syntax and semantics in the language
editor
Program
entry and editing:
The
soft tools used are text editors. Editor function in two modes
1.
Command Mode
It
accepts the user commands specifying the editing function to be performed.
2.
Data Mode
The user keys in the
text to be added to the files.
ü Testing
and Debugging:
Various
task to be performed here are selection of test data for the programs, analysis
of test results to detect errors if any and debugging. Software tools used to
implement these steps are:
1.Test data generators
They
help the user to select test data for the program. Test data is a set of input
values that satisfy the conditions required for correct flow of data.
2.Automated test drivers
Here
the program correctness is verified by subjecting is to a standard set of tests
after every modification. This is called regression testing.
3.Debug Monitors
It is a software
which provides debugging support for a program. It executes the program been debugged under its
control. It also enables the monitor to perform dynamically specified debugging
actions. They perform the following facilities for dynamic debugging:
a)Setting break points in
a program.
b)
Initiate a debug conversation when the
control reaches the break point.
c)Display the value of
variables.
d)
Assign new values to variables.
e)Testing user defined
assertions involving program variables.
Enhancement of program performance:
Program
efficiency depends on efficiency of the algorithm and efficiency of the coding.
Editor comes in different forms:
1)
Line editor
2)
Stream editor
3)
Screen editor
4)
Word processors
5)
Structure editor
6)
Graphical editors
Ø LINE
EDITOR
The
scope of edit operations on line editor is limited to line of text.
The
line is designated:
a)
Positionally
b)
By specifying a serial number in text
Contextually
a)
By specifying a unique character string in it.
The
primary advantage of line editors is there simplicity.
Ø STREAM
EDITOR
A
stream editor views the entire text as a stream of character this permits edit
operations to cross line boundaries. Stream editors typically supports
character oriented , line oriented and context oriented modes. The current
pointer can be manipulated using all these modes.
Ø SCREEN
EDITORS
Line
or stream editors do not display the text in manner it would appear if printed.
Screen editor uses the “What-you-see-is-what-you-get principle. The editor
displays a screen full of text at a time the user can move the cursor over the
screen, position it at a point where we want to perform. Some editing proceeds
with the editing directly. Thus it is possible to see the effect of an edit
operation on screen.
Ø WORD
PROCESSOR
Word
processors are document editors with additional features to produce well
formatted hard copy output. Essential features of word processor are command
for moving, merging of texts and searching and replacing of words. Many word
processors supports spell check options with the adventure of personal
computers. Word processors have seen wide spread use among authors, office
personal and computer professional.
Ø STRUCTURE
EDITOR
A
structure editor incorporate an awareness of the structure of a document .This
is useful in browsing through a document
CASE STUDY OF MS-WORD, DOS EDITOR , VI –EDITOR
Ø DOS
EDITOR
Introduction
1.How to start the Dos
editor.
2.How to create a file in
the editor.
3.What is a batch file.
4.How to create a batch
file.
5.How to execute a batch
file.
What is DOS Editor?
The DOS Editor is used to display , create , print ,
and modify files.
The DOS Editor looks a little like a word process
EDIT
How do you access the DOS Editor?
Type EDIT at the command prompt and press the ENTER
key.
To name a file before starting type EDIT and the filename. Press the ENTER key.
Why do you want to use DOS Editor?
You use the DOS Editor to create Batch Files.
What are Batch Files?
A batch file contains a series of DOS commands.
Batch files have a
.bat extension.
What do you do with a batch file?
Batch file are like icons on a toolbar. They
simplify your life.
Imagine if you had a
room full of computers. You wanted ti perform the same function on each of the
computers. You have a few options.
Sit at each
computer and perform the function.
Build a batch
file. Execute the batch file. Have time to relax before your next project.
How
do you run or execute a batch file?
Type the
batch file name.
There is no
need to type the .bat extension.
How do you
stop or pause a batch file?
Interrupt
batch file: CTRL+S
Cancel batch fil
What are some special batch file commands and what
is the purpose of each?
ECHO OFF
This turns off all DOS commands after the ECHO OFF
command.
If a DOS command has related questions you will see the questions. The only thing you do not see are the DOS commands.
@
ECHO OFF
This turn off all DOS commands including the ECHO
OFF command .
Now , do you understand the
difference between ECHO OFF and @ECHO
OFF?
ECHO OFF - You see ECHO OFF
@ECHO
OFF - You don’t see ECHO OFF
ECHO.
This create a blank line.
ECHO
This display a message
on a monitor.
PAUSE
This pause your
computer until you press any key.
Ø VI
EDITOR
INTRODUCTION
The
VI editor is a screen based editor used by many Unix users . The VI editor has
a powerful feature to aid programmer, but many beginning users avoid using VI
because the different features overwhelm them. This tutorial is written to help
beginning users get accustomed to using the VI editor , but also contains
section relevant to regular users of VI
as well. Examples are provided , and the best way to learn is to try these
examples as well………. There’s no better way than to experience things yourself.
Starting
the VI Editor
The VI editor lets a user
create new files or edit existing files . The command to start the VI editor is
vi, followed by the file name. For example to edit a file called temporary, you would type vi temporary and then return . You can
start VI without a filename , but when you want to save your work , you will
have to save your work , you will have to tell VI which filename to save it
into later
The Two Modes of VI
The first thing most
users learn about the VI editor is that it has two modes : command and insert . The command mode allows the entry of commands
to manipulate text . these commands are usually one or two characters long, and can be entered with
few keystrokes. The insert mode puts
anything typed on the keyboard into the
current file. into insert mode . The most commonly used commands to get into insert
mode are a and i . These VI starts out in command mode. There are several commands that put the VI editor two commands are described below . Once you
are in insert mode , you get out of it by hitting the escape
key . If your terminal does not have an
escape key , ^ [ should work(control-)]. You can hit escape two times in a row
and VI would definitely be in command mode . Hitting escape while you
are already in command mode doesn’t take the
editor out of command mode .
It may beep to tell you that you are already in that mode.
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Study OF VI Editor
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Editor
An editor allows the users to
see a portion of a file on the screen and to modify characters and lines by
simply typing at the cursor position.
Vi editor
¨
Vi stands for visual
¨
It is a full screen editor and allows the user
to view and edit the entire document at the same time.
¨
Vi is case sensitive.
¨
It has powerful undo features.
Modes of Vi editor
Vi editor works in 3 modes
Command
mode
In this mode all the keys pressed by
the user are interpreted to be editor commands. No text is displayed on the
screen even if corresponding keys is pressed on the keyboard.
Insert mode
This mode permits to insert a new text,
editing and replacement of existing text. When Vi editor is in insert mode the
letters typed at the keyboard are echoed on the screen.
Escape mode
Commands typed at the command line.
Starting with Vi editor
Syntax: vi filename
Moving the cursor
The cursor movement commands
are:
Command
|
Action
|
H or backspace
|
Left one
character
|
l or spacebar
|
Right one
character
|
K or -
|
Up one line
|
J or +
|
Down one line
|
I
|
Moves forward a
word
|
#b
|
Moves back a
word
|
#e
|
Moves to the
last character in the word
|
F[character]
|
Moves right to
the specified character in a line
|
T[character]
|
Moves right and
places it one character before the specified character
|
0 or ^
|
Moves to the
beginning of the file
|
#$
|
Moves to the end
of the file
|
L
|
Moves to the
last line of the file
|
G
|
Moves to the
specified line number
|
Editing the file
¨
Open the file using $ vi filename
¨
To add text at the end of the file, position the
cursor at the last character of the file.
¨
Switch from command mode to text input mode by
pressing ‘a’.
¨
Here ‘a’ stands for append.
¨
Inserting text in the middle of the file is
possible by pressing ‘i’. The editor accepts and inserts the typed character
until Esc key is pressed.
Command
|
Purpose
|
I
|
Inserts text
to the left of the cursor
|
I
|
Inserts text
at the beginning of the line
|
A
|
Append text
to the right of the cursor
|
A
|
Appends text
at the end of the line
|
O
|
Appends a
new line below
|
O
|
Appends a
line above
|
Deleting Text
For
deleting a character, move the cursor to the character , press ‘x’. The
character will
disappear.
Command
|
Purpose
|
X
|
Deletes one
character
|
Nx
|
Deletes n
number of characters
|
#x
|
Deletes on
character at the cursor position
|
#X
|
Deletes on the
character before the cursor position
|
D$ or d
|
Deletes a
line from the cursor position to the end of the line
|
D0
|
Deletes from
the cursor position to the starting of the line
|
#dd
|
Deletes the
current line where the cursor is positioned
|
#dw
|
Deletes the
word from the cursor position to the end of the word
|
The undo features
u-undo the recent changes
U- undo all changes in the
current line
Saving text
:w – save the file and remains
in edit mode
:wq – save the file and quits
from edit mode
:q – quit without changes from
edit mode
Quitting vi
Press zz or ‘:wq’ in command
mode.
