Specifying Optional Arguments with default values in Procedures in VB.net
By: Steven Holzner in VB.net Tutorials on 2010-11-17
You also can make arguments optional in VB .NET procedures if you use the Optional keyword when declaring those arguments. Note that if you make one argument optional, all the following arguments must also be optional, and you have to specify a default value for each optional argument (although you can set them to the keyword Nothing if you wish). You specify a default value with = default_value in the procedure's argument list. Here's an example where I'm making the string argument you pass to a Sub procedure named DisplayMessage optional, and giving that argument the default value "Hello from Visual Basic":
Module Module1
Sub Main()
DisplayMessage()
End Sub
Sub DisplayMessage(Optional ByVal strText As String = _
"Hello from Visual Basic")
System.Console.WriteLine(strText)
End Sub
End Module
Now when I call DisplayMessage with no arguments, as in the code above, the default value is used and this code displays:
Hello from Visual Basic
| Tip |
VB6 had a function named IsMissing that would test if an optional argument had been given a value or not, but now that all optional arguments have default values, IsMissing has been removed. You can, however, use the IsNothing function to check if an argument has been set to Nothing. |
Add Comment
This policy contains information about your privacy. By posting, you are declaring that you understand this policy:
- Your name, rating, website address, town, country, state and comment will be publicly displayed if entered.
- Aside from the data entered into these form fields, other stored data about your comment will include:
- Your IP address (not displayed)
- The time/date of your submission (displayed)
- Your email address will not be shared. It is collected for only two reasons:
- Administrative purposes, should a need to contact you arise.
- To inform you of new comments, should you subscribe to receive notifications.
- A cookie may be set on your computer. This is used to remember your inputs. It will expire by itself.
This policy is subject to change at any time and without notice.
These terms and conditions contain rules about posting comments. By submitting a comment, you are declaring that you agree with these rules:
- Although the administrator will attempt to moderate comments, it is impossible for every comment to have been moderated at any given time.
- You acknowledge that all comments express the views and opinions of the original author and not those of the administrator.
- You agree not to post any material which is knowingly false, obscene, hateful, threatening, harassing or invasive of a person's privacy.
- The administrator has the right to edit, move or remove any comment for any reason and without notice.
Failure to comply with these rules may result in being banned from submitting further comments.
These terms and conditions are subject to change at any time and without notice.
- Data Science
- Android
- React Native
- AJAX
- ASP.net
- C
- C++
- C#
- Cocoa
- Cloud Computing
- HTML5
- Java
- Javascript
- JSF
- JSP
- J2ME
- Java Beans
- EJB
- JDBC
- Linux
- Mac OS X
- iPhone
- MySQL
- Office 365
- Perl
- PHP
- Python
- Ruby
- VB.net
- Hibernate
- Struts
- SAP
- Trends
- Tech Reviews
- WebServices
- XML
- Certification
- Interview
categories
Related Tutorials
Changes in Controls from VB6 to VB.net
Unstructured Exception Handling in VB.net
Structured Exception Handling in VB.net
Creating Sub Procedures in VB.net
Passing a Variable Number of Arguments to Procedures in VB.net
Specifying Optional Arguments with default values in Procedures in VB.net
Preserving a Variable's Values between Procedure Calls in VB.net
Throwing an Exception in VB.net
Comments