Byref (Parameters)
Declaration specifier to explicitly pass a parameter by reference
Syntax
`
ByRef param As datatype
`
Usage
`
[ Declare ] { Sub | Function } proc_name ( ByRef param As datatype )
`
Description
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`.
Example
`
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
Sleep
End
`
Dialect Differences

- In -lang fb dialect, `ByVal` is the default parameter passing convention for all built-in types except `String` and user-defined `Type` which are passed `ByRef` by default.
- In -lang qb and -lang fblite dialects, `ByRef` is the default parameter passing convention.

Differences from QB

- New to FreeBASIC

See also

- Passing Arguments to Procedures
- `Declare`
- `ByVal`
- `Byref (Function Results)`