   
   Function    Parametrs        ByVal  ByRef      ByVal ...
      ByVal  ByRef               ByVal ...     ByVal            ByRef  
         ByVal  ByRef        

ByVal :    KeyWord      Function  :
CODE
Public Function Add(ByVal Number1 As Integer,ByVal Number2 As Integer) As Integer

      Number1  Number2         Funcion Add                Function Add ...            
       Click Event    :
CODE
Dim X,Y As Integer
X=15 : Y=10
Add(X,Y)

      Add  X,Y    Add     ...   :         ByVal       .
    100/100                ... 
              ByVal    
       X    Y    Y    X    Swap
CODE
Public Function Swap(ByRef X As Integer,ByRef Y As Integer)
Dim Tmp As Integer
Tmp=X
X=Y
Y=Tmp
End Function

      :
CODE
Dim X As Integer =10
Dim Y As Integer =20
Msgbox " X Value = " & X & VbCrlf & " Y Value = " & Y

Swap(X,Y)

Msgbox " X Value = " & X & VbCrlf & " Y Value = " & Y

    MsgBox     Swap  
CODE
X Value = 10
Y Value = 20

        
     MsgBox      
CODE
X Value = 20
Y Value = 10


              
     ByRef  ByVal   Add         (  )              
       
    

