Operators

1. Arithmetic operators  

The following are the arithmetic operators recognized by BASIC.

TABLE C2.1 Arithmetic Operators

Operators                                 Operation                      Example

 +                                              Addition                          25+10

-                                               Subtraction                      25-10

*                                              Multiplication                  25*10

/                                               Division                            25/10

^                                              Exponentiation                 2^5

2. Relational operators

Relational Operators let you compare two values. The result of the comparison is either true or false. Relational operators are used to compare variables, or constants of the same type for example : 

We can not compare numeric constant with string constant.

There are six relational operators in BASIC. They are mentioned in the table below :

Table C2.2 Relational Operators

Operator                Relation Tested                 Expression

=                            Equality (equal to)             x = y

<>                          Inequality (Not equal to)   x<>y

<                            Less than                          x < y 

>                            Greater than                     x > y

< =                         Less than or equal to        x < = y

> =                        Greater than or equal to    x > = y

3. Logical operators

Logical operators perform tests on multiple relations or Boolean operations.

The logical operator returns a result which is either true or false. There are three commonly used logical operators :

1. AND

2. OR

3. NOT       

Note : Boolean Operation - An operation which functions in accordance with the rules of BOOLEAN ALGEBRA ( A type of mathematics which involves working with binary numbers.

1. AND operator

Table  C 2.3 Truth Table for Results of AND operation

Value                       Value                    Result

 X                                 Y                       X AND Y

 T                                 T                            T

 T                                 F                             F

 F                                 T                             F 

 F                                 F                             F

Table C 2.3 above shows the TRUTH Table for AND operation. As you can see from the table, when the value of both X and Y are TRUE (T) the result of AND operation between X and Y (i.e. X AND Y) is TRUE(T). If any one of the value is FALSE(F), the result is FALSE(F). If both the values are FALSE(F), the result is also FALSE(F).
Note : Truth Table - A mathematical table that states values and units of all possible combinations (Boolean relationship) of output values a function of input.  

2. OR operator

Table C 2.4 Truth Table for Results of OR operation

Value                              Value                        Result

   X                                      Y                           X OR Y

   T                                       T                               T

   T                                       F                                T

   F                                        T                              T

   F                                       F                                F

Table C 2.4 shows the Truth Table for OR Operation. As you see from the table, when the value of  X and Y are True (T), the result of OR operation between X and Y (i.e. X OR Y) is True (T). If any one of the value is TRUE (T), the result is True (T). If both the values are False(F), then the result will be False(F).

3. NOT operator

Table C 2.5 Truth Table for the Result of NOT Operator

Value                               Result

   X                                   NOT X

   T                                       F

   F                                       T

Table C 2.5 shows the Truth Table fro NOT operator. NOT operation has to be performed on a single value. When the value of X is True(T), the result of NOT operation on X (i.e. NOT X) will be FALSE(F). When the value of X is FALSE(F), the result will be TRUE(T). Thus, the result of the NOT operation is the complementary of the given value.

4. String operators

The BASIC interpreter compares strings by taking one character at a time from each string. The ASCII code are used for the comparison purpose. If the ASCII codes in each strings are the same, the strings are equal.

To compare strings. the same relational operators as mentioned before (to compare numbers) can be used.

Table C 2.6 String operators 

Operators                         Meaning                           Example

    =                                     Equal to                           X$ = Y$

  < >                                    Unequal                           X$ < > Y$

   <                                      Less than                         X$  < Y$

   >                                      Greater than                    X$  > Y$

< =                                     Less than and equal to     X$ < = Y$

> =                                    Greater than and equal to  X$ > = Y$

Example 1

"AA" < "AB"

"CLASS 9  = "CLASS 9"

Strings can be connected by using the plus (+) sign.

Example 2

if X$ = "BEAUTI" AND Y$= "FUL"

Both these strings can be combined as :

X$ + Y$ = > BEAUTIFUL