5.6.9.8 Logical Operators

Logical operators are simple data operators that perform bitwise computations on their operands.

 logical-operator-expression = not-operator-expression / and-operator-expression / or-operator-expression / xor-operator-expression / imp-operator-expression / eqv-operator-expression 

Static semantics:

§ Logical operators are statically resolved as simple data operators.

§ A logical operator is invalid if the declared type of any operand is an array or a UDT.

§ For unary logical operators, the operator has the following declared type, based on the declared type of its operand:

Operand Declared Type	Operator Declared Type
Byte	Byte
Boolean	Boolean
Integer	Integer
Any floating-point or fixed-point numeric type, Long, String, String * length or Date	Long
LongLong	LongLong
Variant	Variant

 

§ For binary logical operators, the operator has the following declared type, based on the declared type of its operands:

Left Operand Declared Type	Right Operand Declared Type	Operator Declared Type
Byte	Byte	Byte
Boolean	Boolean	Boolean
Byte or Integer	Boolean or Integer	Integer
Boolean or Integer	Byte or Integer	Integer
Any floating-point or fixed-point numeric type, Long, String, String * length or Date	Any numeric type except LongLong, String, String * length or Date	Long
Any numeric type except LongLong, String, String * length or Date	Any floating-point or fixed-point numeric type, Long, String, String * length or Date	Long
LongLong	Any numeric type, String, String * length or Date	LongLong
Any numeric type, String, String * length or Date	LongLong	LongLong
Any type except an array or UDT	Variant	Variant

 

Runtime semantics:

§ Logical operators are first evaluated as simple data operators.

§ If the value type of any operand is an array, UDT or Error, runtime error 13 (Type mismatch) is raised.

§ Before evaluating the logical operator, its non-Null operands undergo Let-coercion to the operator’s effective value type.

§ For unary logical operators, the effective value type is determined as follows, based on the value type of the operand:

Operand Value Type	Effective Value Type
Byte	Byte
Boolean or Integer or Empty	Integer
Long	Long
LongLong	LongLong
Single	Single
Double or String	Double
Currency	Currency
Date	Date (however, the operand is Let-coerced to Double instead)
Decimal	Decimal
Null	Null

 

§ For binary logical operators, if either operator is null, the effective value type is determined as follows, based on the value types of the operands:

Left Operand Value Type	Right Operand Value Type	Effective Value Type
Byte or Null	Byte	Byte
Byte	Byte or Null	Byte
Boolean or Null	Boolean	Boolean (however, the operands are Let-coerced to Integer instead)
Boolean	Boolean or Null	Boolean (however, the operands are Let-coerced to Integer instead)
Byte, Boolean, Integer, Null or Empty	Integer or Empty	Integer
Integer or Empty	Byte, Boolean, Integer, Null or Empty	Integer
Byte	Boolean	Integer
Boolean	Byte	Integer
Any floating-point or fixed-point numeric type, Long, String, Date or Empty	Any numeric type except LongLong, String, Date, Null or Empty	Long
Any numeric type except LongLong, String, Date, Null or Empty	Any floating-point or fixed-point numeric type, Long, String, Date or Empty	Long
LongLong	Any numeric type, String, Date or Empty	LongLong
Any numeric type, String, Date or Empty	LongLong	LongLong
Null	Null	Null

 

• The value type of a logical operator is determined from the value the operator produces:

  • If the logical operator produces a value other than Null, the operator’s value type is its effective value type. The operator’s result value is Let-coerced to this value type.

  • Otherwise, if the logical operator produces Null, the operator’s value is Null.