Operator Orelse (Short Circuit Inclusive Disjunction)operator

Returns the short circuit-or (Inclusive Disjunction) of two numeric values

Operatorsoperatordocumented

Syntax

Declare Operator OrElse ( ByRef lhs As T1, ByRef rhs As T2 ) As Ret

Parameters

Name		Description
`lhs`		The left-hand side expression.
`T1`		Any numeric or boolean type.
`rhs`		The right-hand side expression.
`T2`		Any numeric or boolean type.
`Ret`		A numeric or boolean type (varies with
`T1`		and
`T2`		).

Return value

Returns the short circuit-or (inclusive disjunction) of the two operands.

Description

This operator evaluates the left hand side expression. If the result is nonzero, then -1 (true) is immediately returned. If the result is zero then the right hand side is evaluated, and the logical result from that is returned, returning -1 (true) for a nonzero value or 0 (false) for zero.
(for conversion of a boolean to an integer, false or true boolean value becomes 0 or -1 integer value)

The truth table below demonstrates all combinations of a short circuit-or operation, the '-' denotes that the operand is not evaluated.

Lhs Value	Rhs Value	Result
0	0	0
0	nonzero	-1
nonzero	(not evaluated)	-1

OrElse equivalent to:
Iif( Lhs = 0, Rhs <> 0 , -1 )

Short-circuiting is performed - only expressions needed to calculate the result are evaluated. The left hand side lhs is evaluated first, and only if it evaluates to zero (false) is the right hand side rhs also evaluated. If the left hand side evaluation lhs returns non-zero (true), it is known that at that point that the overall condition is true, so the right hand side rhs is not evaluated (skipped).

The return type is almost always an Integer, of the value 0 or -1, denoting false and true respectively. Except if the left and right-hand side types are both Boolean, then the return type is also Boolean.

This operator cannot be overloaded for user-defined types.

Remarks

Usage



result = lhs OrElse rhs

Differences from QB

This operator was not available in QB.

Example

'' Using the ORELSE operator to test

'' if a value is out of range



Dim As Integer n

Input "Enter a number between 1 and 10: ", n



Function test(ByVal n As Integer) As Integer

    Print "expression evaluated"

    Return n

End Function



'' print value only if n is in range [1, 10]

If test(n) < 1 OrElse test(n) > 10 Then  '' if n < 1, second expression is not evaluated

    Print "   => out of range"

Else

    Print "   => n ="; n

End If

Sleep

Reference

Documented in KeyPgOpOrElse.html