Elementary Statistics and Computer Application

Relational and Logical Expressions

Relational expressions
BASIC allows the construction and use of relational expressions and are formed by using the relational operators. These operators are
Relational expressions are constructed by combining two arithmetic expressions with relational operators.
The general form is

Where indicates a relational operator.
Eg; A=2, B=3
A = B , A > B A < B
False False True
Relational expression are commonly used to test conditions in IF–THEN ELSE statements.
Logical Expressions
Logical expressions are designed using logical operators and relational expressions. commonly used logical operators are NOT, AND, OR, XOR, EQV. The following tables explain their action. Such tables are called truth tables.
NOT Table




AND Table





XOR table



EQV table



Example

Logical expressions may be used in the IF –THEN & IF –THEN –ELSE statements as test conditions like relational expressions.
The order of evaluation of the operators is as follows