Solved

How Many Parameters ?

Posted on 2002-07-25
7
141 Views
Last Modified: 2010-05-02
I have a function with 2 optional paramters

Public Sub ShowContact(ID As Long, Optional lClientNum As Long, Optional bShowButtons As Boolean = False)


The value of lClientNum can = 0 at times

Sometimes I dont need the lClientNum parameter -

So I need a way to test and see if I have passed lClientNum as a parameter - testing for 0 wont work

Please help

DWE
0
Comment
Question by:DWE
7 Comments
 
LVL 26

Expert Comment

by:EDDYKT
ID: 7177008
ismissing(lClientNum)
0
 
LVL 5

Accepted Solution

by:
bob_online earned 50 total points
ID: 7177094
IsMissing works in VB6 but not vb.net.

A better approach, assuming lClientNum is always positive is

Public Sub ShowContact(ID As Long, Optional lClientNum As Long  = -1, Optional bShowButtons As Boolean = False)

If lClientNum >= 0 Then
  do it

End If

The default value for an optional parameter does NOT have to be 0.

0
 
LVL 1

Expert Comment

by:MrRoper
ID: 7177150
Hmm Bob, In vb.net you should be overloading the sub (i.e. writing to versions, one with one parameter and one with two) and therefore do not need to use optional parameters

Use ismissing for vb6
0
Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

 

Author Comment

by:DWE
ID: 7177169
Thanks guys

Have a great evening

DWE
0
 
LVL 4

Expert Comment

by:Nazdor
ID: 7177171
As bop_online said - use a different value for your default and then test for that value to indicate if the entry is there.

IsMissing will NOT work given your sub declaration, because IsMissing will only work on variant arguments, so you could use:

Public Sub ShowContact(ID As Long, Optional lClientNum As Variant, Optional bShowButtons As Boolean = False)

  If IsMissing(lClientNum) ...


But then you'd have to cast lClientNum to actually use (which may not be a problem), eg:

  If val(lClientNum) = 0 then...




The third (least useful) option is to add another argument which says whether or not to use lClientNum, eg:

Public Sub ShowContact(ID As Long, Optional bUseClientNum as Optional = False, Optional lClientNum As Long, Optional bShowButtons As Boolean = False)

   If bUseClientNum then
      doit



0
 

Author Comment

by:DWE
ID: 7177177
thanks for the additional information - it is appreciated

DWE
0
 
LVL 5

Expert Comment

by:bob_online
ID: 7177452
You're right, IsMissing only works with variants -- I han't had enough coffee yet this morning...
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Introduction While answering a recent question about filtering a custom class collection, I realized that this could be accomplished with very little code by using the ScriptControl (SC) library.  This article will introduce you to the SC library a…
Article by: Martin
Here are a few simple, working, games that you can use as-is or as the basis for your own games. Tic-Tac-Toe This is one of the simplest of all games.   The game allows for a choice of who goes first and keeps track of the number of wins for…
Show developers how to use a criteria form to limit the data that appears on an Access report. It is a common requirement that users can specify the criteria for a report at runtime. The easiest way to accomplish this is using a criteria form that a…
This lesson covers basic error handling code in Microsoft Excel using VBA. This is the first lesson in a 3-part series that uses code to loop through an Excel spreadsheet in VBA and then fix errors, taking advantage of error handling code. This l…

839 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question