ucParamCount

See Also: ucDefineFunction, ucDefineOperator, ucParam, ucParamHandle, ucReturn

Retrieves the number of arguments that are being passed to a Native callback routine. This is useful for functions that can accept any number of arguments.

ucParamCount(ExpressionHandle)

Parameter

ExpressionHandle

All Native callback routines receive one argument, which is ExpressionHandle. This handle is required as the argument of ucParamCount().

Remarks

• Native callback routines (which are significantly faster than non-native callbacks) are intended for Standard License customers (though you can still test it, just like all other features, with the demo).
• ucParamCount is merely a wrapper which looks like this in PowerBASIC:

Function ucParamCount Alias "ucParamCount" (ByVal Expr As ExpressionType Ptr) Export As Dword

Function = @Expr.@ArgList[0].ValuePtr

End Function

Details for using pointers with native callback routines are beyond the scope of this help file.

Example:

The following routine defines a function named MyAverage, which takes an indefinite number of arguments, and returns the average of these numbers. Once defined, MyAverage(3, 4, 5, 6) would return 4.5.

Visual Basic

' The following line can be placed in Form_Load()

ucDefineFunction "Native: MyAverage(x ...)", AddressOf MyAverage

' The following callback routine goes in a separate module, such as DemoVB.Bas

Sub MyAverage(ByVal Expr As Long)

Dim x As Long, Total As Double

For x = 1 To ucParamCount(Expr)

Total = Total + ucParam(Expr, x)

Next

ucReturn Expr, Total / ucParamCount(Expr)

End Sub

Examples for other compilers

New or enhanced in version 2.96

• ucParamCount was optimized for speed.