MsgBox vs MsgBox in VBScript

Question

I m trying to write a VBScript and I m using functions such as Randomize  and MsgBox  I m curious as to what is the difference of using    and not using them  For example   Randomize - This line works   Randomize   - This line works also   MsgBox  Hello world   - This works   MsgBox   Hello world    - This works as well   The script will be running on multiple machines with different versions of Windows  at least Windows XP   I m wondering if I would be getting any compatibility syntax issues in using these functions

User · Answer

You have to distinct sub routines and functions in vba... Generally (as far as I know), sub routines do not return anything and the surrounding parantheses are optional. For functions, you need to write the parantheses.

As for your example, MsgBox is not a function but a sub routine and therefore the parantheses are optional in that case. One exception with functions is, when you do not assign the returned value, or when the function does not consume a parameter, you can leave away the parantheses too.

This answer goes into a bit more detail, but basically you should be on the save side, when you provide parantheses for functions and leave them away for sub routines.

User · Answer

To my knowledge these are the rules for calling subroutines and functions in VBScript    When calling a subroutine or a function where you discard the return value don t use parenthesis When calling a function where you assign or use the return value enclose the arguments in parenthesis When calling a subroutine using the Call keyword enclose the arguments in parenthesis   Since you probably wont be using the Call keyword you only need to learn the rule that if you call a function and want to assign or use the return value you need to enclose the arguments in parenthesis  Otherwise  don t use parenthesis   Here are some examples    WScript Echo 1   two   3 3 - calling a subroutine WScript Echo 1   two   3 3  - syntax error Call WScript Echo 1   two   3 3  - keyword Call requires parenthesis MsgBox  Error  - calling a function  like  a subroutine result   MsgBox  Continue    4  - calling a function where the return value is used WScript Echo  1   2  3    two       3 3    - calling a subroutine where the arguments are computed by expressions involving parenthesis  note that if you surround a variable by parenthesis in an argument list it changes the behavior from call by reference to call by value  WScript Echo 1  - apparently this is a subroutine call using parenthesis but in reality the argument is simply the expression  1  and that is what tends to confuse people that are used to other programming languages where you have to specify parenthesis when calling subroutines I m not sure how to interpret your example  Randomize    Randomize is a subroutine that accepts a single optional argument but even if the subroutine didn t have any arguments it is acceptable to call it with an empty pair of parenthesis  It seems that the VBScript parser has a special rule for an empty argument list  However  my advice is to avoid this special construct and simply call any subroutine without using parenthesis    I m quite sure that these syntactic rules applies across different versions of operating systems

User · Answer

The difference between    and    is   With    you are not calling anything  With    you are calling a sub   Example with sub   Sub   MsgBox  Msg  vbYesNo vbCritical  Title   Select Case Sub      Case   vbYes           MsgBox You said yes       Case   vbNo           MsgBox You said no   End Select   vs Normal    MsgBox This is normal

User · Answer

A callable piece of code  routine  can be a Sub  called for a side effect what it does  or a Function  called for its return value  or a mixture of both  As the docs for MsgBox     Displays a message in a dialog box  waits for the user to click a   button  and returns a value indicating which button the user clicked       MsgBox prompt   buttons    title    helpfile  context     indicate  this routine is of the third kind   The syntactical rules of VBScript are simple   Use parameter list    when calling a  routine as a  Function  If you want to display a message to the user and need to know the user s reponse   Dim MyVar MyVar   MsgBox   Hello World    65   MsgBox Example        MyVar contains either 1 or 2  depending on which button is clicked    Don t use parameter list    when calling a  routine as a  Sub  If you want to display a message to the user and are not interested in the response   MsgBox  Hello World    65   MsgBox Example    This beautiful simplicity is messed up by   The design flaw of using    for parameter lists and to force call-by-value semantics   gt  gt  Sub S n    n   n   1   End Sub  gt  gt  n   1  gt  gt  S n  gt  gt  WScript Echo n  gt  gt  S  n   gt  gt  WScript Echo n  gt  gt  2 2   S  n  does not mean  call S with n   but  call S with a copy of n s value   Programmers seeing that   gt  gt  s    value   gt  gt  MsgBox s     works  are in for a suprise when they try    gt  gt  MsgBox s  65   MsgBox Example    gt  gt  Error Number        1044 Error Description   Cannot use parentheses when calling a Sub   The compiler s leniency with regard to empty    in a Sub call  The  pure  Sub Randomize  called for the side effect of setting the random seed  can be called by  Randomize     although the    can neither mean  give me your return value  nor  pass something by value   A bit more strictness here would force prgrammers to be aware of the difference in  Randomize n   and  Randomize  n    The Call statement that allows parameter list    in Sub calls           s    value      Call MsgBox s  65   MsgBox Example        which further encourage programmers to use    without thinking    Based on What do you mean  cannot use parentheses

User · Answer

You are just using a single parameter inside the function hence it is working fine in both the cases like follows   MsgBox  Hello world   MsgBox   Hello world      But when you ll use more than one parameter  In VBScript method will parenthesis will throw an error and without parenthesis will work fine like   MsgBox  Hello world    vbExclamation   The above code will run smoothly but  MsgBox   Hello world    vbExclamation    will throw an error   Try this    -

[function] MsgBox "" vs MsgBox() in VBScript

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