·       QBASIC
-        QBASIC is an ideal programming language for beginners because of its intuitive commands, simple structure and flexibility.
-        The full form of QBASIC is Quick Beginners All Purpose Symbolic Instructions Code.
-        QBASIC is developed by Microsoft in 1991.
-        The extension of QBASIC is “.bas”.
·       Keywords
-        Predefined word which operation and meaning is defined in compiler. It means we can not use keywords for other uses.
E.g. :- PRINT, INPUT, WHILE, FOR, etc.
·       Variable
-        Variable which value can change according to the users.
-        If we want to take string type (i.e. letter) value in a variable then we must put dollar sign ($). After name of that variable.

*       There are some rules defined for variables :-
-        Keywords are not allowed.
-        Digits are allowed.
-        Variable must be started with alphabet.
-        Blank space are not allowed.
-        Special characters except dot (.) and dollar ($) are not allowed.

*       Variables are of two types in QBASIC
·        Numeric
-        It stores only numeric data.
-        i.e. English book = 100, School = 20000 etc.
·        Alphanumeric
-        It stores only non - numeric data.
-        Its name must be suffix with $ sign.
-        i.e. name$=”Techworld”
·       Constant
-        These are fixed values, which are processed and put it into variable.

*       Constant are of two types in QBASIC
·       Numeric
-        Those data which can be calculated that data is called numeric data.
-        These are numbers.
-        i.e. 34, 45, 9, 23, 89 etc.
·       Alphanumeric
-        Those data which can not be calculated that data is called alphanumeric data.
-        These are represented in double quotation mark { “ “ }.
-        i.e. “Techworld”, “India”, “Bharat”, “6556” etc.
·       Operators
-        It always perform some operation on its operands.
-        Operands are values on which operators perform operation.
-        i.e. +, -, /, *, etc.
·       Operator are classified in four categories in QBASIC

*       Assignment Operators :
-        It is used to assign value to variables.
-        Equal sign { = } is used.
-        e.g. :- fees = 1400, name$=”Rahul”

*       Arithmetic Operators :
-        These operation performs arithmetic operations.

Operators
Operations
+
Used for addition
-
Used for subtraction
*
Used for multiplication
/
Used for division
^ or **
Used for power
Mod (modulus )
Used for remainder

*       Relation Operators :
-        It is used for comparison of its operands.

Operators
Operations
< 
Used for less than comparison
> 
Used for greater than comparison
=
Used for equality comparison
= > or > =
Used for greater than or equality comparison
< = or < =
Used for less than or equality comparison
< > or > <
Used for no equality comparison

*       Logic Operators :
-        It performs logical operations like AND, OR & NOT.
-        AND & OR used for combination more than one relation operator.
-        NOT is used for reverse of resultant.

 AND :-  In this operator, if all condition are true then resultant become true otherwise false.
Condition 1
Condition 2
Resultant
True
True
True
True
False
False
False
True
False
False
False
False



OR :- In this operator, if all condition are false then resultant become false otherwise true.
Condition 1
Condition 2
Resultant
True
True
True
True
False
True
False
True
True
False
False
False






       NOT :-  In this operation, if condition is true then it gives false and if result of condition is false then it gives true.
Condition
Resultant
True
False
False
True





*       Two main command which we use to do our operation’s
1.      Input command :-  It is used for inputting values / data from the keyboard.
        Syntax : INPUT variable1, variable 2,  ……
                      INPUT “Message” ; variable1, variable2, …
        E.g. INPUT  A , B
               INPUT “Enter two value” ; A , B
              INPUT “Enter three values” ; A , B , C

2.      Print command :-  It is used for outputting on or more than one data.
       Syntax : PRINT <data/expression> separator <data/expression> separator
                Comma { , } and semicolon { ; } are used for separators.
       E.g. PRINT rupees, 10, 1200
           PRINT “India” , “Bharat”
           PRINT name$, age