VB -Logical Operators

LOGICAL OPERATORS  So far, we have used only simple conditions with the If/Then/Else statements.  Visual Basic lets you test more than one condition.  To include two or more conditions, the extra conditions have to be linked by logical operators.

 There are three logical operators: 1. AND 2. OR 3. NOT

LOGICAL OPERATORS 1. AND OPERATOR This operator can be illustrated by a simple example. In an office, a person retires on reaching the age of 55. He qualifies for a gold medal if his years of service with the company exceed 12.

AND operator Condition 1

Condition 2

If age = 55 and service >= 12 then result.text = “you retire with a gold medal�

Result if both conditions are true

LOGICAL OPERATORS  In other words, both conditions joined by AND have to be true in order for the statement following THEN to be carried out.

If Condition1 and Condition2 then Statement Condition 1 Condition 2 Statement True

True

Carried out

True

False

Not Carried out

False

True

Not Carried out

False

False

Not Carried out

LOGICAL OPERATORS 2. OR OPERATOR  Another logical operator is OR.  To return to our office example, if the condition for obtaining a gold medal is reaching the age of 55 OR having served the company for more than 12 years, then an employee fulfilling any one of the conditions will qualify for a gold medal.  In other words, if one condition is true, the Then part will be carried out.

LOGICAL OPERATORS If Condition1 or Condition2 then Statement Condition 1 Condition 2 Statement True True Carried out True False Carried out False

True

Carried out

False

False

Not Carried out

LOGICAL OPERATORS 3. NOT OPERATOR  The NOT operator is placed immediately in front of the condition it is to work with.  This operator means exactly what it says, that the condition is not fulfilled.

If Not age < 18 Then statement: means the age is to be more than 18.