Visual Basic.NET How to Program (PDF)

Chapter 7 Arrays 287
7.10 Variable-Length Parameter Lists
It is possible to create procedures that receive a variable number of arguments, using keyword
ParamArray. The program in Fig. 7.18 calls programmer-defined procedure
AnyNumberArguments three times, passing a different number of values each time.
The values passed into procedure AnyNumberArguments are stored in one-dimensional
Integer array array1, which is declared using ParamArray.
Common Programming Error 7.4
Attempting to declare a parameter variable to the right of the ParamArray array variable
is a syntax error. 7.4
Common Programming Error 7.5
Attempting to use ParamArray with a multidimensional array is a syntax error. 7.5
1 ' Fig. 7.18: ParamArrayTest.vb
2 ' Using ParamArray to create variable-length parameter lists.
3
4 Module modParamArrayTest
5
6 Sub Main()
7 AnyNumberArguments()
8 AnyNumberArguments(2, 3)
9 AnyNumberArguments(7, 8, 9, 10, 11, 12)
10
11 End Sub ' Main
12
13 ' receives any number of arguments in array
14 Sub AnyNumberArguments(ByVal ParamArray array1 _
15 As Integer())
16
17 Dim i, total As Integer
18 total = 0
19
20 If array1.Length = 0 Then
21 Console.WriteLine("Procedure AnyNumberArguments" & _
22 " received 0 arguments.")
23 Else
24 Console.Write("The total of ")
25
26 For i = 0 To array1.GetUpperBound(0)
27 Console.Write(array1(i) & " ")
28 total += array1(i)
29 Next
30
31 Console.WriteLine("is {0}.", total)
32 End If
33
34 End Sub ' AnyNumberArguments
35
36 End Module ' modParamArrayTest
Fig. Fig. 7.18 7.18 Creating variable-length parameter lists (part 1 of 2).