An introduction to Computer Programming Contents: Computer programs Qbasic -Features - Rules - Parts - Qbasic Editor screen Commands/ Keywords and their functions Development cycle Program Planning

4. According to Sammet, over
200 programming languages
were developed between1952
and 1972, but she considered
only about 13 of them to be
significant

5. QBASIC is a stripped-down
version of QuickBasic that
Microsoft released in 1991, which
was included for free with MS-
DOS 5 and later versions. It also
comes packed-in with the
Windows 95 and Windows 98
operating systems.
QBASIC is shareware. The latest version is Version 1.1.

8. Every programming language has a set of rules
that have to e followed while writing a program,
following are some rules of QBASIC LANGUAGE.

9. QBASIC editor is the window where you write
programs. The editor provides all the facilities to
write programs and editing them.

10. • MENU BAR.— NAMES EACH MENU. WHEN YOU PRESS THE ALTT
KEY, THE HIGHLIGHTED LETTER INDICATES WHICH KEY "PULLS
DOWN" THAT MENU.
VIEW WINDOW.— DISPLAYS YOUR PROGRAM'S TEXT.
CURSOR.— SHOWS WHERE THE TEXT YOU TYPE WILL APPEAR. THE
CURSOR APPEARS IN THE ACTIVE WINDOW.
MOUSE CURSOR.— SHOWS CURRENT ON-SCREEN POSITION OF
MOUSE (USE WITH MOUSE ONLY).
TITLE BAR.— SHOWS THE NAME OF THE PROGRAM OR
PROCEDURE.
MAXIMIZE BOX.— EXPANDS THE ACTIVE WINDOW TO FILL THE
SCREEN (USE WITH MOUSE ONLY).
SCROLL ARROW.— SCROLLS THE TEXT ONE CHARACTER OR ONE
LINE AT A TIME (USE WITH MOUSE ONLY).
SCROLL BOX.— SHOWS CURSOR'S RELATIVE POSITION WITHIN THE
FILE OR PROCEDURE.
Menu
Bar
View
Window
Mouse
Cursor
Cursor
Title
Bar
Maximize
Box
Scroll
Arrow
Scroll
Box

11. IMMEDIATE WINDOW.—
• EXECUTES QBASIC STATEMENTS DIRECTLY; THEY NEED NOT BE ENTERED AS PART OF A
PROGRAM.
CAPS LOCK AND NUM LOCK INDICATORS.—
• C APPEARS WHEN THE CAPS LOCK KEY IS TOGGLED ON. NAPPEARS WHEN THE NUM LOCK KEY IS
TOGGLED ON.
SCROLL BARS.—
• SCROLLS TEXT IN THE CURRENTLY ACTIVE WINDOW (USE WITH MOUSE ONLY).
REFERENCE BAR.—
• CONTAINS REFERENCE INFORMATION. THE FIRST FIVE ITEMS ARE BUTTONS SHOWING A
FREQUENTLY USED SHORTCUT KEY AND THE CORRESPONDING MENU OR OPTION. CLICKING A
BUTTON WITH THE MOUSE GIVES THE SAME RESULT AS PRESSING THE SHORTCUT KEY SHOWN
IN THE BUTTON. PRESSING ALT DISPLAYS FOUR DIFFERENT REFERENCE ITEMS.
WORDSTAR-STYLE COMMAND INDICATOR.—
• ^Q APPEARS WHEN YOU ENTER CTRL+Q, A WORDSTAR-STYLE COMMAND. ^K APPEARS HERE
WHEN YOU ARE SETTING A PLACE MARKER (SEE SECTION 12.4, "USING PLACEMARKERS IN
TEXT"). ^P APPEARS HERE WHEN YOU ARE ENTERING A LITERAL CHARACTER (SEE SECTION 12.6 ,
"ENTERING SPECIAL CHARACTERS").

12. It is possible to overwrite lines
with the new statements, but if
you want to write a totally new
program use a NEW command.
• is the command used to execute the program and
get the output on the screen.

13. COMMAND/KEYWORDS IN QBASIC AND THEIR
FUNCTIONS:
List
-Used to
list the
program
on the
screen
RUN
-Used to
execute
the
program
LList
-Used to
list the
program
as a
hardcopy
LPrint
-Used to
get the
output of
the
program
on the
hardcopy
New
-Used
to clear
the
memor
y of the
existing
program
System
-Used
to take
you
back to
dos
prompt
Save
-Used
to save
the
program
Load
-Used
to load
the
progra
m from
the disk
to the
memory

14. Commands
With the PRINT command, you can also print numbers to the screen. Delete the current
program (unless you already have) and write the following:
PRINT 555 (or ?555)
<press Enter>
Press F5 to run the program. The program outputs:
555

15. • access to drop down menus by:
– using mouse
– pressing ALT key highlights shortcut keys
e.g. F, E, V etc. to menus; highlighted
letters in menu are shortcuts
• ESC key to return to View Screen
ALT + enter to maximise
screen
Ctrl + break to stop a
continuously looping
program

16. determine outputs - what is the question?
determine inputs - what is the user
required to enter/ data available?
determine process - algorithm /
mathematical formulas
Algorithm
- step by step
solution to the
problem

17.  Analysis - define the program
 Design - plan the solution; consider all
‘what if scenarios’
 Code - translate into (QBasic) language
 Test and Debug
 DOCUMENTATION!!!!! • Flowcharts
• Pseudocode
• Top-down
• charts

18. • represents the
steps in
the algorithm in a
graphical manner

19. • http://ayushchoithram.wikispaces.com/QBasic+Intro
duction
• http://ayushchoithram.wikispaces.com/QBasic+Intro
duction
• http://chortle.ccsu.edu/QBasic/AppendixB/appendix
B.html
• http://www.qbasic.net/

20. Leigh-ann Garrote
Aileen Jeanne Gumop-
as
#78 Brgy. Santiago,
Binalonan
Pangasinan
#05 Brgy. Sta. Catalina,
Binalonan
Pangasinan