When you think ASP, think...
Recent Articles
All Articles
ASP.NET Articles
Related Web Technologies
User Tips!
Coding Tips

Sample Chapters
JavaScript Tutorials
MSDN Communities Hub
Official Docs
Stump the SQL Guru!
XML Info
Author an Article

The 4 Guys Present: ASPFAQs.com

Jump to a FAQ
Enter FAQ #:
..or see our 10 Most Viewed FAQs.

4GuysFromRolla.com : ASP FAQS : Functions and Subroutines


Why are there certain times when I can use parenthesis when calling a Subroutine, and other times not?

[Print this FAQ]

Answer: In VBScript, the general rule is that you cannot place parenthesis around the arguments you are calling a sub with, unless you prefix the subroutine call with the Call keyword like so:

'This will generate an error
MySub(Param1, Param2, Param3)

'To use parens for a Sub, you must use the Call statement
'This is legal syntax
Call MySub(Param1, Param2, Param3)

However, if this is true, then why can you sometimes use parens when calling subroutines? For example, Response.Write is a subroutine call, and the VBScript engine doesn't barf when you do:

'This works... but should it?
Response.Write("My text...")

Shouldn't you need to prefix the above line of code with the Call statement? Notice that the only time VBScript doesn't barf when using parens when calling a sub is when you are passing just one parameter and the parameter can be evaluated as an expression (a string, integer, equation, etc.). This is because, according to the VBScript language rules, when it sees parens around a parameter to a sub, it assumes you want to evaluate what is in the parens first, and pass that information to the sub. Such behavior removes the ambiguity between these two statements:

MySub 4 + 5
MySub (4 + 5)

The first line will call MySub passing a value of 4 and adding 5 to the result. The second line will pass in the value of 9 to MySub. Note that the parens didn't cause an error (even though MySub is a sub, and shouldn't allow such behavior). This is because such syntax is interpretted to evaluate the expression 4 + 5 and then pass the value into the Sub.

For more information on this phenomenon, be sure to read the great article: Using Parenthesis in VBScript when Calling a Subroutine.

FAQ posted by Scott Mitchell at 9/27/2000 3:40:42 AM to the Functions and Subroutines category. This FAQ has been viewed 51,170 times.

Do you have a FAQ you'd like to suggest? Suggestions? Comments? If so, send it in! Also, if you'd like to be a FAQ Admin (creating/editing FAQs), let me know! If you are looking for other FAQs, be sure to check out the 4Guys FAQ and Commonly Asked Messageboard Questions!

Most Viewed FAQs:

1.) How can I format numbers and date/times using ASP.NET? For example, I want to format a number as a currency. (761643 views)
2.) I am using Access and getting a 80004005 error (or a [Microsoft][ODBC Microsoft Access Driver] The Microsoft Jet database engine cannot open the file '(unknown)' error) when trying to open a connection! How can I fix this problem? (207777 views)
3.) How can I convert a Recordset into an array? Also, how can I convert an array into a Recordset? (202549 views)
4.) How can I quickly sort a VBScript array? (196039 views)
5.) How can I find out if a record already exists in a database? If it doesn't, I want to add it. (156019 views)
6.) How do I display data on a web page using arrays instead of Do...While...MoveNext...???... (152331 views)
7.) When I get a list of all files in a directory via the FileSystemObject, they aren't ordered in any reasonable way. How can I sort the files by name? Or by size? Or by date created? Or... (140381 views)
8.) For session variables to work, must the Web visitor have cookies enabled? (110162 views)
9.) Can I send emails without using CDONTS? (107083 views)
10.) How can I take the result of a SELECT...MULTIPLE or a group of same-named checkboxes and turn it into a query? That is, if the user selects 3 answers, how can I construct a query that looks for all 3? (106308 views)
Last computed at 9/17/2007 3:22:00 AM

ASP.NET [1.x] [2.0] | ASPFAQs.com | Advertise | Feedback | Author an Article