What is the "best" way to determine the number of elements in an array in VBScript?
UBound() tells you how many slots have been allocated for the array, but not how many are filled--depending on the situation, those may or may not be the same numbers.
First off there is no predefined identifier called vbUndefined as the currently accepted answer appears to imply. That code only works when there is not an Option Explicit at the top of the script. If you are not yet using Option Explicit then start doing so, it will save you all manner of grief.
The value you could use in place of vbUndefined is Empty, e.g.,:-
If arr(x) = Empty Then ...
Empty is a predefined identify and is the default value of a variable or array element that has not yet had a value assigned to it.
However there is Gotcha to watch out for. The following statements all display true:-
MsgBox 0 = Empty
MsgBox "" = Empty
MsgBox CDate("30 Dec 1899") = True
Hence if you expect any of these values to be a valid defined value of an array element then comparing to Empty doesn't cut it.
If you really want to be sure that the element is truely "undefined" that is "empty" use the IsEmpty function:-
If IsEmpty(arr(x)) Then
IsEmpty will only return true if the parameter it actually properly Empty.
There is also another issue, Null is a possible value that can be held in an array or variable. However:-
MsgBox Null = Empty
Is a runtime error, "invalid use of null" and :-
MsgBox IsEmpty(Null)
is false. So you need to decide if Null means undefined or is a valid value. If Null also means undefined you need your If statement to look like:-
If IsEmpty(arr(x)) Or IsNull(arr(x)) Then ....
You might be able to waive this if you know a Null will never be assigned into the array.
I'm not aware of a non-iterative method to do this, so here's the iterative method:
Function countEmptySlots(arr)
Dim x, c
c = 0
For x = 0 To ubound(arr)
If arr(x) = vbUndefined Then c = c + 1
Next
countEmptySlots = c
End Function
As Spencer Ruport says, it's probably better to keep track yourself to begin with.
There's nothing built in to tell you what elements are filled. The best way is to keep track of this yourself using a count variable as you add/remove elements from the array.
Related
I am writing a chess program and has to see whether certain value are empty. I tried
aPiece is an array of CommandButtons. cmdSquare is a control array of shapes.
Private aPiece(63) As CommandButton
...
For p = 0 To 63
If IsEmpty(aPiece(p)) Then
aPiece(p).Left = cmdSquare(p).Left
aPiece(p).Top = cmdSquare(p).Top
End If
Next p
All variable are declared and is seem to be IsEmpty function which is not working.
The IsEmpty method only returns meaningful information for variants. Since the array contains objects, you need to check like this:
If aPiece(p) Is Nothing Then
However, this seems like only part of the answer. The above logic is saying "If there is no piece in my array then update it's location". That doesn't make sense to me and will generate an error. You also need to add Not like below:
For p = 0 To 1
If Not aPiece(p) Is Nothing Then
aPiece(p).Left = cmdSquare(p).Left
aPiece(p).Top = cmdSquare(p).Top
End If
Next p
It depends on the datatype of aPiece. If it is a variant and you haven't assigned a value to it, IsEmpty will return true. However, if it is a String, Date, Integer, etc. those are automatically initialized (String will be an empty string, Integer will be 0) so IsEmpty will return false.
A pretty good reference is this page: IsEmpty Function - Visual Basic 6.0
I have to be honest that I don't quite understand Lua that well yet. I am trying to overwrite a local numeric value assigned to a set table address (is this the right term?).
The addresses are of the type:
project.models.stor1.inputs.T_in.default, project.models.stor2.inputs.T_in.default and so on with the stor number increasing.
I would like to do this in a for loop but cannot find the right expression to make the entire string be accepted by Lua as a table address (again, I hope this is the right term).
So far, I tried the following to concatenate the strings but without success in calling and then overwriting the value:
for k = 1,10,1 do
project.models.["stor"..k].inputs.T_in.default = 25
end
for k = 1,10,1 do
"project.models.stor"..j..".T_in.default" = 25
end
EDIT:
I think I found the solution as per https://www.lua.org/pil/2.5.html:
A common mistake for beginners is to confuse a.x with a[x]. The first form represents a["x"], that is, a table indexed by the string "x". The second form is a table indexed by the value of the variable x. See the difference:
for k = 1,10,1 do
project["models"]["stor"..k]["inputs"]["T_in"]["default"] = 25
end
You were almost close.
Lua supports this representation by providing a.name as syntactic sugar for a["name"].
Read more: https://www.lua.org/pil/2.5.html
You can use only one syntax in time.
Either tbl.key or tbl["key"].
The limitation of . is that you can only use constant strings in it (which are also valid variable names).
In square brackets [] you can evaluate runtime expressions.
Correct way to do it:
project.models["stor"..k].inputs.T_in.default = 25
The . in models.["stor"..k] is unnecessary and causes an error. The correct syntax is just models["stor"..k].
I am running into the Type Mismatch error when I attempt to call a function I created.
Example:
Function DoThis(paramA, paramB, paramC)
If paramA = "Something" Then
DoThis = DoSomething
ElseIf paramA = "This" Then
DoThis = DoSomethingDifferent
Else
DoThis = DoThisOtherThing
End If
End Function
Dim result: result = DoThis(valueA, ValueB, ValueC)
Can anyone see what my mistake could be? Other functions are working correctly. I have double checked the spelling by actually copying and pasting the function name where I call it. I have verified that the function name is not used anywhere else, i.e., as a constant or something else.
Note that when debugging this the ValType for all arguments is vbString. Also I am never able to enter the function, so it is not like I am debugging the function, enter it and then get the type mismatch.
ty.
VBScript has only one data type called a Variant. A Variant is a special kind of data type that can contain different kinds of information, depending on how it is used. Because Variant is the only data type in VBScript, it is also the data type returned by all functions in VBScript.
There are some subtypes of data that a Variant can contain (e.g. Empty, Null, string, integer, object, array etc.) You can use some conversion functions to convert data from one subtype to another, if that conversion is not implicit in VBScript. Now, pay your attention to real, factual data subtype of True and vbTrue.
The True keyword (boolean literal) has a value (inner representation) equal to -1.
On the other hand, vbTrue is one of few built-in constants and, in despite of it's name, has a subtype of Integer! It's one of so-called Tristate Constants:
Constant Value Description
vbUseDefault -2 Use default from computer's regional settings.
vbTrue -1 True
vbFalse 0 False
I hope next code could make clear all above statements:
Wscript.Echo _
vbTrue, CStr( vbTrue), VarType( vbTrue), TypeName( vbTrue) , _
vbNewLine, True, CStr( True), VarType( True), TypeName( True)
However, used with If _condition_ Then ..., there are some particularities; in brief:
The Then part of the If ... statement conditionally executes groups of statements only when a single test If condition is not False, i.e. any non-zero number esteems to be true, not only -1. Therefore you are able to use whatever variable or expression (numeric or string) you choose as long as the result is numeric...
Summarizing: If _expr_ Then ... is the same as
If CBool(_expr_) Then ...
The reason why retval is retuning mismatch error because it has a numeric value and an alpha value and wsh does not like that.
A sure way to get a type mismatch error for the published code is to define DoSomething etc. as Subs (which seems probable, given the names).
I cannot explain why this was a problem, but today I reduced the function down to a simple boolean return value and I still got the type mismatch error.
So I then created a new function with the same parameters and such. When I changed the call to the new function the error goes away.
My original function with the simple boolean return:(MISMATCH ERROR)
Function IsInstalledCheck(valueToCheck, expectedValue, checkType)
IsInstalledCheck = vbFalse
End Function
My new function with the a simple return:(Works)
Function IsItemInstalled(valueToCheck, expectedValue, checkType)
IsItemInstalled = vbFalse
End Function
EDIT
Note that I had tried this with the standard True / False values as well. The solution was to simply recreated the same function with a new name and for whatever magical reason that worked. The function signature was the same, the order of variables, variable names, the test conditions, everything in the body of the new function is the same.
I have declared a two dimensional array in the function library and associated it with a test. In action1 of the test, I tried to clear the array using "erase" statement.
My code -
In Function Library,
Dim strVerifyAry(25,6)
In action1,
erase strVerifyAry
Error message
Run Error - Type mismatch: 'Erase'
How to clear the contents of this array?
Works for me in plain VBScript, so it's most likely an issue with whatever engine QTP uses for running VBScript code. You should be able to emulate the behavior of Erase for a 2-dimensional array like this:
Sub EraseArray(ByRef arr)
For i = 0 To UBound(arr, 1)
For j = 0 To UBound(arr, 2)
If IsObject(arr(i, j)) Then
Set arr(i, j) = Nothing
Else
arr(i, j) = Empty
End If
Next
Next
End Sub
Or like this, if you don't want to set fields containing objects to Nothing:
Sub EraseArray(ByRef arr)
For i = 0 To UBound(arr, 1)
For j = 0 To UBound(arr, 2)
arr(i, j) = Empty
Next
Next
End Sub
I do not exactly understand why, but you can create a sub like
Public Sub DoErase (byRef Ary)
Erase Ary
End Sub
in the library, and call it from within the action like this:
DoErase StrVerifyAry
and that works.
Update: No it doesn't. The array is successfully passed to DoErase, and the DoErase call works fine, but the test afterwards still can reference the array elements that Erase was supposed to be erasing.
If the test declares the array, it works fine (Erase erases the elements).
This is very strange and probably has to do with the quirky scopes in function libraries.
Please let us know if you ever find out what's going on here...
This drove me nuts for an entire afternoon so I wanted to post an answer for future reference. I filled an array using the Split command and then needed to Erase it before the script looped back through the process again. Nothing I tried would erase or clear the array and the next use of Split just appended to the previous array elements.
By trying the 'array=Nothing' loop above, I finally managed to generate a "This array is fixed or locked" error which I researched. Turns out I had used the array in a 'For Each..Next' loop which locks the array so it can't be erased or cleared. More info is available HERE:
You can use a Dictionary collection rather than an array in some circumstances. Then use RemoveAll when you want to clear it. That doesn't help when your array was created by a split function, or whatever, but it can help in other use cases.
Set myDict = CreateObject("Scripting.Dictionary")
...
myDict.RemoveAll
Refer to: https://www.w3schools.com/asp/asp_ref_dictionary.asp
I am writing a VBScript that automatically interacts with some web pages. I am having trouble at the final step where the script needs to click on a link to make a booking. The link for each time will only be available if that time is free. The idea of my code is to simply select the first time available (I originally though I could do this by using Mid() and GetElementId as I know the first 7 chars of each link ID but couldn't get this working). The array contains the IDs for all possible times available in a day. Some will already have been taken so that ID will no longer exist on the form.
I have 2 problems:-
1) Neither getElementBy Id or the Document.All.Item().Click commands will accept an element from the array - I get an Object Required run time error.
2) If getElementId doesn't find a matching ID it simply throws an Object required error. I wasn't expecting this, I thought that my elem variable would be nothing or null and that I could test for this.
Can anyone give me any pointers?
'This is a shortened version of my array- there are lots more times!
Times(0)="bookBtn0810"
Times(1)="bookBtn0818"
Times(2)="bookBtn0826"
Dim TimeAvail
Dim i
Dim elem
TimeAvail = "No"
i = 0
Do While (TimeAvail = "No") or (i<3)
Set elem = IE.Document.GetElementById(Chr(34) & Times(i) & Chr(34)) 'Chr(34) is to add ""
if elem is nothing then
TimeAvail = "No"
i=i+1
else
TimeAvail = "Yes"
IE.Document.All.Item(Chr(34) & Times(i) & Chr(34)).click
end if
Loop
Now, unless I'm being very silly, you won't be able to sit a variable to a non-existent element.
The only thing I can think of is to add:
On Error Resume Next
At the beginning, so it skips the error message. You may need to handle the error separately yourself.