2. You've probably used computers to play games, and to write
reports for school. It's a lot more fun to create your own
games to play on the computer. This book will help you get
started by using QBASIC. QBASIC is a programming
language. With a programming language you can tell the
computer what you want it to do. It's a lot like giving
someone directions to your house. The computer follows each
step and does exactly what you tell it. By programming the
computer you can solve math problems, create art or music,
and even make new games. It's all up to you.
The best way to start with this book is to type in some of
the small programs you'll find in each of the chapters. You
might need to work through Chapter 1 first. An adult can
help you get up to speed quickly. Then change the programs
to do what you want them to do. Before long, you'll be
writing your own programs.
3. BASIC is a programming language used for beginners.
It is very easy ad simple to understand .
BASIC stands for Beginners All Purpose Symbolic
Instruction Code. it was developed in Dartmouth
college, New Hampshire, USA by professor John G .
Kemeny and Thomas E. Kurtz in may 1964.
4. The main components of the given qbasic program
are:-
COMMENTS: Any text written after REN is
treated as a comments as you wish.
PROGRAM BODY: It contains the programming
statements which cause the action to be taken.
5. •Let us write our first and very simple QBASIC program.
•Double click on the QBASIC icon on the Desktop to start
QBASIC.
•The QBASIC window will appear with Welcome dialog box.
•Press the Esc key to hide the Welcome dialog box.
•The first window of QBASIC appears.
•Type the program, as shown in the above picture.
•QBASIC executes the program line-by-line. If it
finds any error, it displays the error message and stops
execution.
6. 1. Click on FILE menu and select SAVE AS option .
2. Give a meaningful name to your program in the file name:
text box and press ENTER key.
3. Your file will be saved with the name given by you and
with extension .BAS will be added to automatically .
4. The file name should not exceed more then 8 characters.
7. RUN A PROGRAM
There are many ways to run a program in QBASIC:-
•By pressing F5 key.
•By selecting RUN menu and then click on start option .
•By typing RUN in the immediate mode and pressing ENTER
key.
8. A character set is a set of symbols that can be used in
programming language . BASIC uses the followings
symbols as its character set :-
1. ALPHABET-> A,B,C,D…………………Z
a,b,c,d………………….z
2. NUMBERS-> 1,2,3,4,5,6,7,8,9,0
3. SPESIAL CRAACTER-> !,@,#,$,%,^,&,*,(,),_,+,},{, etc.
9. CONSTANTS- The value which do not change during the
execution of program is called constant . Constants are of
two types:
1. NUMRIC CONSTANTS – Any numeric value ,an integer or
real numbers ,positive or negative numbers is called a
numeric constant .For Example 224,+12,-85 etc.
2. ALPHANUMRIC CONSTANTS- A set of characters is
called a STRING. An alphanumeric or string constant
consists of a sequence of characters ,A-Z, a-z,0-9 and
certain special symbols like %^&*( );:” ‘/.For example
“RAGHAV” ,”SUM =Rs84’,”94”.
10. A variable is a location in a memory to which any value can be assigned .
1. NUMERIC VARIABLE: It can contain only numeric values .It
represented by an alphabet or an alphabetfollowed by an
another aialphabet or a digit. It should not contain any space
or symbols like ^,?,,/, @ etc. Underscore can be used
whenever a space is required. For example A, C, A2, ABC etc.
represent numeric variables.
2. ALPHANUMERIC OR STRING VARIABLE : A string variable
is represented by an alphabet followed by dollar ($) singn. For
example A1$, RKL$ etc.
11. 1. ARITHMETIC OPERATORS :
OPRETOR EXPLANATION EXAMPLE RESULT(SP
OSE A= 8, B=4)
+ To add 2 or more
numbers
Sum = a+ b 12
- To subtract two or
more numbers
Sub = a - b 4
* To multiply two or
more numbers
Mul = a*b 32
/ To divide two or
more numbers
Div = a / b 2
^ To calculate
Exponentiation
value
Exp = a ^ b 512
12. 2. RELATIONAL OEPRATORS:
OPRETORS MEANING EXAMPLE RESULT(SP
OSE A=10,B=8)
= A = B FALSE
<> A<>B TRUE
> A>B TRUE
< A<B FALSE
>= A>=B TRUE
<= A<=B FALSE
13. 3. LOGICAL OPERATORS : Logical operators are used to
perform logical opertion on numerical values. Logical operators
are used to combine two or more relational expressions and
return a single value as TRUE or FALSE in a decision. The
common logical operations are : AND, OR, NOT.
•Hierarchy defines the order in which the operators are
executed in any Basic expression. The full form of
BEDMAS is:-
14. B BRACETS ()
E Exponentiation ^
D DIVISION /
M MULTIPLICATION *
A ADDITION +
S SUBTRACTION -
The assignment statement or
Let statement, is used to assign
a value to a variable. In
QBASIC, using Let statement
and line numbers are optional.
CLS
THIS COMMAD IS USED TO
CLER SCREEN
15. PRINT COMMAND
•The print command is used to display any message or value.
• The print command is used to display any message or value.
• The print command is used with different variations to print
the output in different forms.
• Print using semicolon is used to print the values one after
another, without any space in between.
• This allows the printing of values one after another with plenty
of spaces in between. Only five values can be printed in one line.
In case of more than five values, the remaining values will be
printed on the next line.
• The TAB function is used to move the print position to the
column indicated in its argument. This statement is quite suitable
for printing tabular type of results. PRINT TAB statement can
be used in controlling column location.
• If you want to leave blank line in between while printing an
output, use PRINT statement in the following way.
16. INPUT STATEMENT
The INPUT statement in QBASIC, accepts the data item
from the user. This statement asks the user to make data
entry while the program is being executed.
While using INPUT statement, the computer does the
following things:
• It stops further processing of the program
• It prints a question mark on the screen.
• It waits for the user to key in its response and press
Enter key.
•It stores or assigns the same data item in to the
corresponding variable mentioned in the INPUT statement.
