Double indirection in VB? Equivalent to C++ pointers?

[nath]

How can I access the content of a variable/constant X when I use a variable Y which contains the name of the first variable, i.e. X?
Similarly how can I run a function/procedure if I call it using a variable containing its name?
I know there are many alternative ways to do that, but I'd like to know if someone is aware of how to do exactly
what I need (No public variables, no arrays).

I want to do something like the following:

'*******
Public const MYCONST1 = "Portfolio1.txt"
Public const MYCONST2 = "Portfolio2.txt"

Sub Test()
	Dim i as Integer

	For i = 1 to 2
		Open "MYCONST" & i For Input as #1	
		'I want it to open Portfolio1.txt and Portfolio2.txt but it will try to open 
		'MYCONST1 and MYCONST2 instead, which are not existing files!
	Next i
End Sub
'*******

A similar problem is:

Sub Test2()
	...
	sType = "Rectangle"	
	...
	Call "Print" & sType 	'I want it to call the procedure PrintRectangle
End Sub

Sub PrintRectangle()
	...
End Sub

'********************

Thank you for your help.

Nath.

 

[heico]

For the first problem, use an array. Something like this

dim arrFiles(1) as string

arrFiles(0)="Portfolio0.txt"
arrFiles(1)="Portfolio1.txt"

For i=0 to ubound(arrFiles)
Open arrFiles(i) For Input as #1
Close #1
Next

I don't think you can start procedures using a variable, but it doesn't seem very usefull either.

Hope it helps a bit,

Heico

 

[AdaHacker]

Sounds like what you're looking for is a macro substitution thing like they have in FoxPro. Sorry, but this simply doesn't exist in VB. As far as I know, there's no way to call internal functions by a string containing the name, and the closest thing to getting values from variable names is collections, which probably isn't what you're really looking for.

 

[nath]

Yes it is indeed the idea of macro substitution.
It was also my impression it doesn't exist in VB but I couldn't believe it... There many ways round the problem, but never very neat. Never mind. Thanks for your input/confirmation.

 

[WilMead]

[tt]
const cFiles = _
&quot;&MYCONST1.txt<REC>&MYCONST2.txt<REC>&MYCONST3.dat&quot;

Dim fList() as String, fName as String
Dim I as Integer

fList = Split( _
Replace(cFiles, &quot;&MYCONST&quot;, &quot;Portfolio&quot, _
&quot;<REC>&quot; _
)

Open fList(I)...
Open format(I, &quot;\P\o\r\t\f\o\l\i\o0\.\t\x\t&quot...
[/tt]



Wil Mead
wmead@optonline.net

 

[strongm]

There are some quite neat methods of solving this with the Scripting Host control, and its eval and executestatement methods