18.4.9 Logical operators

The logical operator provides logical AND && and OR (||).

Organization of this subsection

(1) Format
(2) Description
(3) Example of coding

(1) Format

Logical AND operation

expression-1 && expression-2

Logical OR operation

expression-1 || expression-2

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(2) Description

Logical operators do not perform normal arithmetic conversion. Instead, it evaluates the operands in terms of whether they match 0. The result of a logical operation is true or false. The result is the bool type.

The following explains the logical operators.

Operator	Description
`&&`	If both the operands are `true`, the result is `true`. If one of the operands is `false`, the result is `false`. If the first operand for logical AND is `false`, the second operand is not evaluated.
`\|\|`	If both the operands are `false`, the result is `false`. If one of the operands is `true`, the result is `true`. If the first operand for logical OR is `true`, the second operand is not evaluated.

The operands for logical AND and OR expressions are evaluated from the left to the right. If the operational result can be identified only by the value for the first operand, the second operand is not evaluated. This is referred to as quick evaluation.

(a) Logical AND operator (&&)

If both the expressions evaluate to true, the result is true. If one of the expressions is evaluates to false, the result is false. The following table shows how the results are evaluated.

Evaluation of expression 1	Evaluation of expression 2	Resulting evaluation
true	true	true
true	false	false
false	true	false
false	false	false

(b) Logical OR operator (||)

If one or both of the expressions evaluate to true, the result is true. The following table shows how the results are evaluated.

Evaluation of expression 1	Evaluation of expression 2	Resulting evaluation
true	true	true
true	false	true
false	true	true
false	false	false

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(3) Example of coding

DEFINE
{
   float varfloat1 = 1.567e-1;
   integer varint1 = 10;
   integer varfloat2 = 0;
   integer varint2 = 0;
   bool varbool;
   integer WINH;
}
MAIN
{
   varbool = varfloat1 && varint1;
   AIT_LogMessage("The expected value of varbool is: true");
   varbool =varfloat2 && varint1;
   AIT_LogMessage("The expected value of varbool is: false");
   varbool=varfloat1 && varint2;
   AIT_LogMessage("The expected value of varbool is: false");
   varbool=varfloat2 && varint2;
   AIT_LogMessage("The expected value of varbool is: false");
}

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