__FB_ARG_COUNT__
 
Intrinsic define (macro) performed by the compiler.

Syntax

__FB_ARG_COUNT__( args... )

Parameters

args...
argument list

Description

Counts the number of arguments in the argument list (args...) and returns the corresponding value.
A value is always returned, with 0 corresponding to an empty argument list.

Because the argument separator is the comma (,), the returned value for a non-empty argument list is the number of main commas (non-nested) plus 1.

Example

#macro m( args... )
    Print __FB_ARG_COUNT__( args )
#endmacro

m()
m(a)
m(b,c)
m(,d)
m(,e,)
m(,,,)

Sleep

/' Output:
 0
 1
 2
 2
 3
 4
'/
    

' macro with a variadic parameter which can contain several sub-parameters:
'   To distinguish between the different arguments passed by a variadic_parameter,
'   you can first convert the variadic_parameter to a string using the Operator # (Preprocessor Stringize),
'   then differentiate in this string (#variadic_parameter) each passed argument by locating the separators (usually a comma)
'   in a [For...Next] loop based on the number of arguments (__FB_ARG_COUNT__) passed to the macro.

#macro average(result, arg...)
    Scope
        Dim As String s = #arg
        If s <> "" Then
            result = 0
            For I As Integer = 1 To __FB_ARG_COUNT__( arg ) - 1
                Dim As Integer k = InStr(1, s, ",")
                result += Val(Left(s, k - 1))
                s = Mid(s, k + 1)
            Next I
            result += Val(s)
            result /= __FB_ARG_COUNT__( arg )
        End If
    End Scope
#endmacro

Dim As Double result
average(result, 1, 2, 3, 4, 5, 6)
Print result

Sleep

/' Output :
 3.5
'/
    

Version

  • Since fbc 1.08.0

Differences from QB

  • New to FreeBASIC

See also