Checking if a value is a member of a list - vba

I have to check a piece of user input against a list of items; if the input is in the list of items, then direct the flow one way. If not, direct the flow to another.
This list is NOT visible on the worksheet itself; it has to be obfuscated under code.
I have thought of two strategies to do this:
Declare as an enum and check if input is part of this enum, although I'm not sure on the syntax for this - do I need to initialise the enum every time I want to use it?
Declare as an array and check if input is part of this array.
I was wondering for VBA which is better in terms of efficiency and readability?

You can run a simple array test as below where you add the words to a single list:
Sub Main1()
arrList = Array("cat", "dog", "dogfish", "mouse")
Debug.Print "dog", Test("dog") 'True
Debug.Print "horse", Test("horse") 'False
End Sub
Function Test(strIn As String) As Boolean
Test = Not (IsError(Application.Match(strIn, arrList, 0)))
End Function
Or if you wanted to do a more detailed search and return a list of sub-string matches for further work then use Filter. This code would return the following via vFilter if looking up dog
dog, dogfish
In this particular case the code then checks for an exact match for dog.
Sub Main2()
arrList = Array("cat", "dog", "dogfish", "mouse")
Debug.Print "dog", Test1("dog")
Debug.Print "horse", Test1("horse")
End Sub
Function Test1(strIn As String) As Boolean
Dim vFilter
Dim lngCnt As Long
vFilter = Filter(arrList, strIn, True)
For lngCnt = 0 To UBound(vFilter)
If vFilter(lngCnt) = strIn Then
Test1 = True
Exit For
End If
Next
End Function

Unlike in .NET languages VBA does not expose Enum as text. It strictly is a number and there is no .ToString() method that would expose the name of the Enum. It's possible to create your own ToString() method and return a String representation of an enum. It's also possible to enumerate an Enum type. Although all is achievable I wouldn't recommend doing it this way as things are overcomplicated for such a single task.
How about you create a Dictionary collection of the items and simply use Exist method and some sort of error handling (or simple if/else statements) to check whether whatever user inputs in the input box exists in your list.
For instance:
Sub Main()
Dim myList As Object
Set myList = CreateObject("Scripting.Dictionary")
myList.Add "item1", 1
myList.Add "item2", 2
myList.Add "item3", 3
Dim userInput As String
userInput = InputBox("Type something:")
If myList.Exists(userInput) Then
MsgBox userInput & " exists in the list"
Else
MsgBox userInput & " does not exist in the list"
End If
End Sub
Note: If you add references to Microsoft Scripting Runtime library you then will be able to use the intelli-sense with the myList object as it would have been early bound replacing
Dim myList As Object
Set myList = CreateObject("Scripting.Dictionary")
with
Dim myList as Dictionary
Set myList = new Dictionary
It's up to you which way you want to go about this and what is more convenient. Note that you don't need to add references if you go with the Late Binding while references are required if you want Early Binding with the intelli-sense.
Just for the sake of readers to be able to visualize the version using Enum let me demonstrate how this mechanism could possibly work
Enum EList
item1
item2
item3
[_Min] = item1
[_Max] = item3
End Enum
Function ToString(eItem As EList) As String
Select Case eItem
Case EList.item1
ToString = "item1"
Case EList.item2
ToString = "item2"
Case EList.item3
ToString = "item3"
End Select
End Function
Function Exists(userInput As String) As Boolean
Dim i As EList
For i = EList.[_Min] To EList.[_Max]
If userInput = ToString(i) Then
Exists = True
Exit Function
End If
Next
Exists = False
End Function
Sub Main()
Dim userInput As String
userInput = InputBox("type something:")
MsgBox Exists(userInput)
End Sub
First you declare your List as Enum. I have added only 3 items for the example to be as simple as possible. [_Min] and [_Max] indicate the minimum value and maximum value of enum (it's possible to tweak this but again, let's keep it simple for now). You declare them both to be able to iterate over your EList.
ToString() method returns a String representation of Enum. Any VBA developer realizes at some point that it's too bad VBA is missing this as a built in feature. Anyway, you've got your own implementation now.
Exists takes whatever userInput stores and while iterating over the Enum EList matches against a String representation of your Enum. It's an overkill because you need to call many methods and loop over the enum to be able to achieve what a simple Dictionary's Exists method does in one go. This is mainly why I wouldn't recommend using Enums for your specific problem.
Then in the end you have the Main sub which simply gathers the input from the user and calls the Exists method. It shows a Message Box with either true or false which indicates if the String exists as an Enum type.

Just use the Select Case with a list:
Select Case entry
Case item1,item2, ite3,item4 ' add up to limit for Case, add more Case if limit exceeded
do stuff for being in the list
Case Else
do stuff for not being in list
End Select

Related

VBA Function Passing Multi Variables back to Sub

I have a large string over 500 char which is called strEssay. I want to use a function(since I will need to look for several patterns) to return two values if (for example the name) Frank is found or not.
This is the function I'm trying to use:
Function NameFinder(strEssay as String, strName as String)
Dim varNameCounter as Variant
Dim strNameFinderResult as String
varNameCounter = 0
strNameFinderResult = ""
If strEssay like "*" & strName & "*" Then
strNameFinderResult = strName
varNameFinderCounter = 1
Else
strNameFinderResult = ""
varNameFinderCounter = .001
EndIf
End Function
I want to be able to return back to my subroutine both 'strNameFinderResult' and 'varNameFinderCounter'.
Is there any way that I can return both values?
If I can't return both simultaneously can I return one through the function and the other through a textbox or something? What would calling the function look like in the subroutine and/or how would I need to change my function?
NameFinder() function, returning array of 3 elements. It is called and returned by TestMe(), writing the following to the console:
Function NameFinder(essay As String, name As String)
Dim nameFinderResult As String
Dim namefinderCounter As String
nameFinderResult = "" & essay & name
namefinderCounter = 0.001 + 12
NameFinder = Array(nameFinderResult, namefinderCounter, "something else")
End Function
Public Sub TestMe()
Dim myArray As Variant
myArray = NameFinder("foo", "bar")
Dim i As Long
For i = LBound(myArray) To UBound(myArray)
Debug.Print myArray(i)
Next i
End Sub
As a general rule, you have to give the routine a type like this:
Function NameFinder(strEssay as String, strName as String) as string
But, that returns only ONE value.
So, a function (as opposed to a sub) returns one value (as a general rule).
However, you CAN also return parameters that you pass. I mean, in above, you can't make TWO assignments to one variable, can you?
So, you can use a Sub like this:
Sub NameFinder(strEssay as String, strName as String, _
strNameFinderResult as string, _
varNameFinderCounter as double)
If strEssay like "*" & strName & "*" Then
strNameFinderResult = strName
varNameFinderCounter = 1
Else
strNameFinderResult = ""
varNameFinderCounter = .001
EndIf
So in code, you now can go:
dim strMyResult as string
dim strFinderCount as Double
Call NameFinder("MyEassy", "Joe Blow", strMyResult, strFinderCount)
So, you can return values with the parameters.
Now, I suppose it possible for some strange reason, that you want to use a function to return two values with a single assignment?
What you would do is this in your code module.
Define a custom type, and use that.
eg this:
Option Compare Database
Option Explicit
Type SearchResult
strName As String
FindCount As Double
End Type
Function NameFinder(strEssay As String, strName As String) As SearchResult
NameFinder.FindCount = 0
NameFinder.strName = ""
If strEssay Like "*" & strName & "*" Then
NameFinder.strName = strName
NameFinder.FindCount = 1
Else
NameFinder.strName = ""
NameFinder.FindCount = 0.001
End If
End Function
So, now to use in code? You can go like this:
dim MyResults as SearchResult
MyResults = NameFinder("My eassy", "Joe Blow")
debug.print "Name found result = " & MyResults.strName
debug.print "Count of find = " & MyResult.FindCount
The VERY nice thing about above is you get full intel-sense in your code editor.
eg this:
So by building a custom data type, you can use "one" assignment for the return type. And you get nice type checking and inteli-sense in the VBA code editor.
And you can even do this:
But, to get both variables, then you would in theory wind up calling the function two times. So, you can actually use the function without declarer of variables like this:
Debug.Print NameFinder("MyEassy", "Joe blow").strName
Debug.Print NameFinder("MyEassy", "Joe blow").FindCount
So, I don't recommend the above, but in the case in which you ONLY want one of the return values, then the raw expression (function) like above would be a use case (and no need to even declare a return variable).
But, without a doubt, define a custom type in code as per above. The reason is now you get a really nice VBA editor type-checking, inteli-sense, and also that you only have to declare "one" variable that holds two values.
In fact, the results are very much like JavaScript, or even c# in which you declare a "class" type. So with a custom "type" you are declaring a data type of your own. And the beauty of this is if you need say 3 values, then once again you create a type with 3 "inside" values.
The you ONLY have to declare that one variable as the custom type.
With this you get:
Very valuable compile time syntax and data type checking of the var types you are using.
You get GREAT VBA inteli-sense while coding - which means less coding mistakes.
And you type far less typing in the VBA editor as it will pop-up the choices for you as you write code. And you can't type or choose the wrong sub - type, as the compiler will catch this.

Array of variables declared as string

I have a query regarding creating an array of variables declared as string.
Below is my code. On debugging, the variables show no value.
Need help..
Module Module1
Public Status, PartStat, HomeStat, ClampStat, SldCylStat, PrsCylP1Stat,
PrsCylP2Stat, PrsCylP3Stat, PrsCylP4Stat, PunchStat, SysInProc, Home1,
Home2, Home3, CyclTim, TrqP1Stat, TrqP2Stat, TrqP3Stat, TrqP4Stat,
AngleP1Stat, AngleP2Stat, AngleP3Stat, AngleP4Stat As String
Function AutoReadStatus()
Dim StatArray = {HomeStat, ClampStat, SldCylStat, Home1, PrsCylP4Stat,
PrsCylP2Stat, Home2, PrsCylP3Stat, PrsCylP1Stat, Home3, PunchStat,
AngleP4Stat, AngleP2Stat, AngleP3Stat, AngleP1Stat, TrqP4Stat,
TrqP2Stat, TrqP3Stat, TrqP1Stat}
Status = ReadMultiReg(FormAuto.SP1, "03", "1258", "0013")
For i = 0 To ((Status.Length / 4) - 1)
StatArray(i) = CInt("&H" & Status.Substring(i * 4, 4))
Next
Return Nothing
End Function
End Module
It is not even showing the index of any variable from above array..
Label1.Text = Array.IndexOf(StatArray, SldCylStat)
When you assign a new value to the item inside the array, you assign a new value to the item inside the array (pun intended).
What that means is that item's array now reference the string (or rather the Integer implicitely converted to string as you don't have Option Strict On) you gave and the precedent reference (on your public field) is dropped.
Test this sample code and I think you will understand
Public item As String
Sub Test()
Dim array = {item}
Console.WriteLine(array(0) Is item) ' True
array(0) = "new value"
Console.WriteLine(array(0) Is item) ' False
End Sub
You can see now array(0) reference another object than the one referenced by the item field
As for how to solve it,yYou could pass all those string ByRef that way assignment inside the method would reflect outside of it but that would be tedious.
A "better" way IMO, would be to make a type (a Class) to hold all those string and pass an instance of that type to your method, that way you just mutate the same existing object.
Quick, contrived example :
Class SomeType
Property Item As String
End Class
Sub Test(instance As SomeType)
instance.Item = "new value"
End Sub
' Usage
Dim sample As New SomeType
' here sample.Item is Nothing
Test(sample)
' here sample.Item is "new value"

Set a type in VBA to nothing?

I have defined a variable with an own type, say
Dim point As DataPoint
Public Type DataPoint
list as Collection
name as String
number as Integer
End Type
and I want to delete all values of the variable point at once. If it was a class, I would just use Set point = New DataPoint, or set Set point = Nothing, but how can I proceed if it's a type?
You can benefit from the fact that functions in VB have an implicit variable that holds the result, and that contains the default type value by default.
public function GetBlankPoint() as DataPoint
end function
Usage:
point = GetBlankPoint()
The standard way is to reset each member to its default value individually. This is one limitation of user-defined types compared to objects.
At the risk of stating the obvious:
With point
Set .list = Nothing
.name = ""
.number = 0
End With
Alternatively, you can create a "blank" variable and assign it to your variable each time you want to "clear" it.
Dim point As DataPoint
Dim blank As DataPoint
With point
Set .list = New Collection
.list.Add "carrots"
.name = "joe"
.number = 12
End With
point = blank
' point members are now reset to default values
EDIT: Damn! Beaten by JFC :D
Here is an alternative to achieve that in 1 line ;)
Dim point As DataPoint
Dim emptyPoint As DataPoint
Public Type DataPoint
list As Collection
name As String
number As Integer
End Type
Sub Sample()
'~~> Fill the point
Debug.Print ">"; point.name
Debug.Print ">"; point.number
point.name = "a"
point.number = 25
Debug.Print ">>"; point.name
Debug.Print ">>"; point.number
'~~> Empty the point
point = emptyPoint
Debug.Print ">>>"; point.name
Debug.Print ">>>"; point.number
End Sub
SNAPSHOT
One-liner:
Function resetDataPoint() As DataPoint: End Function
Usage:
point = resetDataPoint()
Another option is to use the reserved word "Empty" such as:
.number= Empty
The only issue is that you will need to change the number from integer to variant.
Using classes in VBA is usually a good practice in case it is not a single purpose solution or the class do not contain too many private attributes because if you want to adhere on OOP rules and keep your class safe, you should declare all the Let and Get properties for all private attributes of class. This is too much coding in case you have more than 50 private attributes. Another negative side of using classes in excel is fact, that VBA do not fully support the OOP. There is no polymorfism, overloading, etc.) Even you want to use an inheritance, you have to declare all the attributes and methods from the original class in the inherited class.
So in this case I would prefer the solution suggested by Jean-François Corbett or GSeng, i.e. to assign an empty variable of the same UDT as the variable you want to clear or to use a function which to me seems little bit more elegant solution because it will not reserve permanent memory for the emtpy variable of your UDT type.
For that is better to use classes, you can declare a class module with the name of your type, then declare all of your members as public, then automatically you can set to nothing and new for create and delete instances.
syntax will be somthing like this after you create the class module and named like your type:
'
Public List as Collection
Public Name as String
Public Number as Long
Private Sub Class_Initialize()
'Here you can assign default values for the public members that you created if you want
End Sub

Hidden features of VBA

Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
Which features of the VBA language are either poorly documented, or simply not often used?
This trick only works in Access VBA, Excel and others won't allow it. But you can make a Standard Module hidden from the object browser by prefixing the Module name with an underscore. The module will then only be visible if you change the object browser to show hidden objects.
This trick works with Enums in all vb6 based version of VBA. You can create a hidden member of an Enum by encasing it's name in brackets, then prefixing it with an underscore. Example:
Public Enum MyEnum
meDefault = 0
meThing1 = 1
meThing2 = 2
meThing3 = 3
[_Min] = meDefault
[_Max] = meThing3
End Enum
Public Function IsValidOption(ByVal myOption As MyEnum) As Boolean
If myOption >= MyEnum.[_Min] Then IsValidOption myOption <= MyEnum.[_Max]
End Function
In Excel-VBA you can reference cells by enclosing them in brackets, the brackets also function as an evaluate command allowing you to evaluate formula syntax:
Public Sub Example()
[A1] = "Foo"
MsgBox [VLOOKUP(A1,A1,1,0)]
End Sub
Also you can pass around raw data without using MemCopy (RtlMoveMemory) by combining LSet with User Defined Types of the same size:
Public Sub Example()
Dim b() As Byte
b = LongToByteArray(8675309)
MsgBox b(1)
End Sub
Private Function LongToByteArray(ByVal value As Long) As Byte()
Dim tl As TypedLong
Dim bl As ByteLong
tl.value = value
LSet bl = tl
LongToByteArray = bl.value
End Function
Octal & Hex Literals are actually unsigned types, these will both output -32768:
Public Sub Example()
Debug.Print &H8000
Debug.Print &O100000
End Sub
As mentioned, passing a variable inside parenthesis causes it to be passed ByVal:
Sub PredictTheOutput()
Dim i&, j&, k&
i = 10: j = i: k = i
MySub (i)
MySub j
MySub k + 20
MsgBox Join(Array(i, j, k), vbNewLine), vbQuestion, "Did You Get It Right?"
End Sub
Public Sub MySub(ByRef foo As Long)
foo = 5
End Sub
You can assign a string directly into a byte array and vice-versa:
Public Sub Example()
Dim myString As String
Dim myBytArr() As Byte
myBytArr = "I am a string."
myString = myBytArr
MsgBox myString
End Sub
"Mid" is also an operator. Using it you overwrite specific portions of strings without VBA's notoriously slow string concatenation:
Public Sub Example1()
''// This takes about 47% of time Example2 does:
Dim myString As String
myString = "I liek pie."
Mid(myString, 5, 2) = "ke"
Mid(myString, 11, 1) = "!"
MsgBox myString
End Sub
Public Sub Example2()
Dim myString As String
myString = "I liek pie."
myString = "I li" & "ke" & " pie" & "!"
MsgBox myString
End Sub
There is an important but almost always missed feature of the Mid() statement. That is where Mid() appears on the left hand side of an assignment as opposed to the Mid() function that appears in the right hand side or in an expression.
The rule is that if the if the target string is not a string literal, and this is the only reference to the target string, and the length of segment being inserted matches the length of the segment being replaced, then the string will be treated as mutable for the operation.
What does that mean? It means that if your building up a large report or a huge list of strings into a single string value, then exploiting this will make your string processing much faster.
Here is a simple class that benefits from this. It gives your VBA the same StringBuilder capability that .Net has.
' Class: StringBuilder
Option Explicit
Private Const initialLength As Long = 32
Private totalLength As Long ' Length of the buffer
Private curLength As Long ' Length of the string value within the buffer
Private buffer As String ' The buffer
Private Sub Class_Initialize()
' We set the buffer up to it's initial size and the string value ""
totalLength = initialLength
buffer = Space(totalLength)
curLength = 0
End Sub
Public Sub Append(Text As String)
Dim incLen As Long ' The length that the value will be increased by
Dim newLen As Long ' The length of the value after being appended
incLen = Len(Text)
newLen = curLength + incLen
' Will the new value fit in the remaining free space within the current buffer
If newLen <= totalLength Then
' Buffer has room so just insert the new value
Mid(buffer, curLength + 1, incLen) = Text
Else
' Buffer does not have enough room so
' first calculate the new buffer size by doubling until its big enough
' then build the new buffer
While totalLength < newLen
totalLength = totalLength + totalLength
Wend
buffer = Left(buffer, curLength) & Text & Space(totalLength - newLen)
End If
curLength = newLen
End Sub
Public Property Get Length() As Integer
Length = curLength
End Property
Public Property Get Text() As String
Text = Left(buffer, curLength)
End Property
Public Sub Clear()
totalLength = initialLength
buffer = Space(totalLength)
curLength = 0
End Sub
And here is an example on how to use it:
Dim i As Long
Dim sb As StringBuilder
Dim result As String
Set sb = New StringBuilder
For i = 1 to 100000
sb.Append CStr( i)
Next i
result = sb.Text
VBA itself seems to be a hidden feature. Folks I know who've used Office products for years have no idea it's even a part of the suite.
I've posted this on multiple questions here, but the Object Browser is my secret weapon. If I need to ninja code something real quick, but am not familiar with the dll's, Object Browser saves my life. It makes it much easier to learn the class structures than MSDN.
The Locals Window is great for debugging as well. Put a pause in your code and it will show you all the variables, their names, and their current values and types within the current namespace.
And who could forget our good friend Immediate Window? Not only is it great for Debug.Print standard output, but you can enter in commands into it as well. Need to know what VariableX is?
?VariableX
Need to know what color that cell is?
?Application.ActiveCell.Interior.Color
In fact all those windows are great tools to be productive with VBA.
It's not a feature, but a thing I have seen wrong so many times in VBA (and VB6): Parenthesis added on method calls where it will change semantics:
Sub Foo()
Dim str As String
str = "Hello"
Bar (str)
Debug.Print str 'prints "Hello" because str is evaluated and a copy is passed
Bar str 'or Call Bar(str)
Debug.Print str 'prints "Hello World"
End Sub
Sub Bar(ByRef param As String)
param = param + " World"
End Sub
Hidden Features
Although it is "Basic", you can use OOP - classes and objects
You can make API calls
Possibly the least documented features in VBA are those you can only expose by selecting "Show Hidden Members" on the VBA Object Browser. Hidden members are those functions that are in VBA, but are unsupported. You can use them, but microsoft might eliminate them at any time. None of them has any documentation provided, but you can find some on the web. Possibly the most talked about of these hidden features provides access to pointers in VBA. For a decent writeup, check out; Not So Lightweight - Shlwapi.dll
Documented, but perhaps more obscure (in excel anyways) is using ExecuteExcel4Macro to access a hidden global namespace that belongs to the entire Excel application instance as opposed to a specific workbook.
You can implement interfaces with the Implements keyword.
Dictionaries. VBA is practically worthless without them!
Reference the Microsoft Scripting Runtime, use Scripting.Dictionary for any sufficiently complicated task, and live happily ever after.
The Scripting Runtime also gives you the FileSystemObject, which also comes highly recommended.
Start here, then dig around a bit...
http://msdn.microsoft.com/en-us/library/aa164509%28office.10%29.aspx
Typing VBA. will bring up an intellisense listing of all the built-in functions and constants.
With a little work, you can iterate over custom collections like this:
' Write some text in Word first.'
Sub test()
Dim c As New clsMyCollection
c.AddItems ActiveDocument.Characters(1), _
ActiveDocument.Characters(2), _
ActiveDocument.Characters(3), _
ActiveDocument.Characters(4)
Dim el As Range
For Each el In c
Debug.Print el.Text
Next
Set c = Nothing
End Sub
Your custom collection code (in a class called clsMyCollection):
Option Explicit
Dim m_myCollection As Collection
Public Property Get NewEnum() As IUnknown
' This property allows you to enumerate
' this collection with the For...Each syntax
' Put the following line in the exported module
' file (.cls)!'
'Attribute NewEnum.VB_UserMemId = -4
Set NewEnum = m_myCollection.[_NewEnum]
End Property
Public Sub AddItems(ParamArray items() As Variant)
Dim i As Variant
On Error Resume Next
For Each i In items
m_myCollection.Add i
Next
On Error GoTo 0
End Sub
Private Sub Class_Initialize()
Set m_myCollection = New Collection
End Sub
Save 4 whole keystrokes by typing debug.? xxx instead of debug.print xxx.
Crash it by adding: enum foo: me=0: end enum to the top of a module containing any other code.
Support for localized versions, which (at least in the previous century) supported expressions using localized values. Like Pravda for True and Fałszywy (not too sure, but at least it did have the funny L) for False in Polish... Actually the English version would be able to read macros in any language, and convert on the fly. Other localized versions would not handle that though.
FAIL.
The VBE (Visual Basic Extensibility) object model is a lesser known and/or under-utilized feature. It lets you write VBA code to manipulate VBA code, modules and projects. I once wrote an Excel project that would assemble other Excel projects from a group of module files.
The object model also works from VBScript and HTAs. I wrote an HTA at one time to help me keep track of a large number of Word, Excel and Access projects. Many of the projects would use common code modules, and it was easy for modules to "grow" in one system and then need to be migrated to other systems. My HTA would allow me to export all modules in a project, compare them to versions in a common folder and merge updated routines (using BeyondCompare), then reimport the updated modules.
The VBE object model works slightly differently between Word, Excel and Access, and unfortunately doesn't work with Outlook at all, but still provides a great capability for managing code.
IsDate("13.50") returns True but IsDate("12.25.2010") returns False
This is because IsDate could be more precisely named IsDateTime. And because the period (.) is treated as a time separator and not a date separator. See here for a full explanation.
VBA supports bitwise operators for comparing the binary digits (bits) of two values. For example, the expression 4 And 7 evaluates the bit values of 4 (0100) and 7 (0111) and returns 4 (the bit that is on in both numbers.) Similarly the expression 4 Or 8 evaluates the bit values in 4 (0100) and 8 (1000) and returns 12 (1100), i.e. the bits where either one is true.
Unfortunately, the bitwise operators have the same names at the logical comparison operators: And, Eqv, Imp, Not, Or, and Xor. This can lead to ambiguities, and even contradictory results.
As an example, open the Immediate Window (Ctrl+G) and enter:
? (2 And 4)
This returns zero, since there are no bits in common between 2 (0010) and 4 (0100).
Deftype Statements
This feature exists presumably for backwards-compatibility. Or to write hopelessly obfuscated spaghetti code. Your pick.

Excel VBA - Initializing Empty User Types and Detecting Nulls

I have created a user defined type to contain some data that I will use to populate my form. I am utilizing an array of that user defined type, and I resize that array as I pull data from an off-site server.
In order to make my program easier to digest, I have started to split it into subroutines. However, when my program is initialized, I cannot tell when a particular array has been initialized, and so I cannot be certain that I can call a size function to see if the array is empty.
Is there a way to initialize an empty user type or detect a null user type? Currently, I am hard-coding it in and I would prefer a more elegant solution.
In addition to isempty(array) solution -
If IsNull(array) then
msgbox "array is empty"
End If
AFAIK, you cannot check whether user-defined type was initialized before it was sent as an argument to a procedure/function.
I am quoting this example from VBA help
Type StateData
CityCode(1 To 100) As Integer ' Declare a static array.
County As String * 30
End Type
The County field is initialized to some value, which you can use a base value.
If the user sets this field explicitly, it means it holds some value & remains uninitialized, otherwise.
for e.g.
Sub main()
Dim example As StateData
MsgBox IsInitialized(example)
Dim example2 As StateData
example2.County = "LA"
MsgBox IsInitialized(example2)
End Sub
Function IsInitialized(arg As StateData) As Boolean
Dim initCounty As String * 30
IsInitialized = (arg.County <> initCounty)
End Function
Try:
dim v
if isempty(v) then
msgbox "is empty"
end if
If myObjectVariable is Nothing
should work to detect if an object has been initialized.
Edit: "is nothing" DOES work, if it is an object variable:
Dim blah As Object
If blah Is Nothing Then
MsgBox "blah is nothing!"
End If
Dim foo as variant
If IsEmpty(foo) Then
MsgBox "foo is empty!"
End If
If you need to check whether the whole dynamic array of custom types was initialized or not (not just particular element) in VBA, then this might not be possible directly (as none of the IsEmpty etc. functions works on custom types). However you might be able to easily restructure your program to return an array of custom types of size 0 to indicate that nothing was read/initialized.
Private Function doStuff() As customType()
Dim result() As customType
' immediately size it to 0 and assing it as result
ReDim result(0)
doStuff = vysledek
' do real stuff, ... premature "Exit Function" will return an array of size 0
' possibly return initialized values
End Function
' then you can all
If (UBound(tabulky) = 0) Then
MsgBox "Nope, it is not initialized."
End If