BYREF (parameters)

Declaration specifier to explicitly pass a parameter by reference

Byref param as datatype

[ declare ] { sub | function } proc_name ( Byref param as datatype )

Passes a variable by reference, that is its address, to a subroutine or function. When a variable is passed by reference, the contents of the variable can be changed by the target subroutine or function.

In -lang qb and -lang fblite dialects, Byref is the default parameter passing convention, unless Option ByVal is in effect.

Opposite of ByVal.

Note: A constant or a literal expression can also be passed to such a procedure (which gets by reference), but they are obviously not modifiable from the procedure body. In that case, the compiler passes by reference a temporary variable initialized with the constant or the literal expression.

Warning: When passing by reference, it is recommended to pass an argument of the same type (or fully compatible, like a derived type for example) as that of the declared parameter. Although in some cases the compiler accepts to pass a different type, often the result is not the one expected.

Dim MyVar As Integer

Sub ChangeVar(ByRef AVar As Integer)
    AVar = AVar + 1
End Sub

MyVar = 1
Print "MyVar: "; MyVar 'output = 1
ChangeVar MyVar
Print "MyVar: "; MyVar 'output = 2

Dialect Differences:
Differences from QB:
See also:
Back to Procedures
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