I would like to know if there is an equivalent of Python's pass statement in VBA.
I am using Excel 2016.
The use of Stop (see this answer) seems to be the best thing to do if you are looking for some "non-statement" that you can use to insert a breakpoint, because the Stop command causes the code to break when it is reached, i.e. you don't even need to mark it as a breakpoint because it is one.
You might also like to consider using Debug.Assert some_logical_expression, which will break automatically whenever the logical expression evaluates to False. So Debug.Assert False would be equivalent to Stop, and Debug.Assert x = 3 would be equivalent to If x <> 3 Then Stop.
In Python you need the Pass, because otherwise the methods will not run.
In VBA, its perfectly ok if you leave an empty method like this:
Public Function Foo() As String()
End Function
Maby you are looking for the "Stop" statement.
The good thing about it is that it doesn't clear your variables.
It depends what are you trying to achieve.
You may declare a Label and then use GoTo Label e.g. declare a label (like Skip:)in your code where you want to jump if a condition is met and then use GoTo Skip
Below is the small demo code to give you an idea about this...
Dim i As Long
For i = 1 To 10
If i = 5 Then GoTo Skip
MsgBox i
Next i
Skip:
Related
Is there a command equivalent to readLine of Java in VBA.
I want to use the text input in the immediate window and put it in a variable.
Is it possible?
You can't use the Immediate Window interactively. For one thing -- while a sub is running it won't accept any keyboard input. You can, however, use it to pass data to a sub or function when you invoke it, so in a sense you can "scrape" data that is there already. Something along these lines:
Sub AddNums(ParamArray nums())
Dim total As Double
Dim i As Long
For i = 0 To UBound(nums)
total = total + nums(i)
Next i
Debug.Print total
End Sub
For example:
Beyond that -- you could move the input-gathering phase to a VBScript script running in console mode, invoke it from VBA, and use either a file (which the script writes to) or perhaps the clipboard to get the data from the script after it is done running. This should be feasible, though it is probably better to find a more idiomatic (form-based) way to do it within VBA.
I am not quite sure why you need to write from Immediate Window to a variable at a runtime - is it some weird debugging practices?
Normally, if you need to take an input you end up with a form to interact with an user.
However, if you do need to write to a variable at a runtime consider the following:
Sub Main()
Dim immediateInput As String
Dim readImmediate As Boolean
Do While (readImmediate = False)
readImmediate = True
Loop
End Sub
now, set a breakpoint at the readImmediate = true line and add immediateInput to the Watch. Bring up both the Immediate Window and Watches and run the macro.
When the runtime hits the breakpoint enter the below in the Immediate Window:
immediateInput = "hello world"
Now have a look in the Watches; your immediateInput's value should be "hello world".
To start off, I know that using Goto is never a good idea. But I'm having a hard time seeing the difference between the following structures...All of them process conditions sequentially, stop processing when they find a true value, then return control to a specified location in the code (the next line, as that's where this particular 'GoTo' target is). What is the difference between:
Ifs with GoTo:
If ConditionA then 'This is designed to skip the evaluation of condition B if condition A is met.
Do something
Goto Resume
End If
If ConditionB then
Do something
Goto Resume
End If
Resume:
Select Case:
Select ConditionIsTrue 'This will also skip the evaluation of B if A is true.
Case A
Do something
Case B
Do something
End select
Separate sub:
EvaluateConditions(condition)
Sub EvaluateConditions(condition)
If A then
DoSomething
Exit Sub
End If
If B then
DoSomething
Exit Sub
End If
End Sub
In general,
'goto' transfers the control of execution to the label that you are assigning. The control never comes back to where you use 'goto'. As the program flow is altered altogether, it is not advisable to use 'goto'. It becomes hard to debug.
When you write a subroutine and call it from other part of your code, the control is transferred back to the called part of your code once the execution of subroutine is complete. Hence, unlike goto, the program flow will not be affected and is always advisable to use subroutines instead of goto.
In case of select statement, it is not much different from multiple 'if-else' statements. Instead of having too many 'if-else' you can use 'select' to have a more cleaner code.
Being specific to what you have asked, all three does the same and there is no difference as such. What you choose depends on your requirement, number of conditions, re-usability of the piece of code and future enhancements.
If you have a very few conditions ( 2 or 3) and if you are sure that the piece of code doesn't require future enhancements, it is 'ok' to use goto.(still not a great choice)
If the piece of code should be reusable or even otherwise, using subroutine is the best choice. In fact, even if you have a very few conditions, it is better to use 'select' statement within the subroutine so that your code looks clean and is easy to add further conditions in future.
The Problem
I am trying to debug some code, and somewhere in the middle I stopped at a breakpoint. Now I want to change some variables and run a certain loop several times.
How far did I get?
I know how to change the variables, but somehow I get stuck when trying to run the loop in the immediate window. Here is an example:
Dim i As Integer
Dim j As Integer
For i = 0 To 6
j=i ' Do something
Next i
I tried several variations of the code, but each time I get the following error:
Compile error: Next without for
Other relevant information
I tried searching but mostly found information about problems with loops, whilst I am quite sure the loop itself is fine. (Especially as I reached it before arriving at the breakpoint).
The only place I saw someone addres this situation, he reduced the loop to a single line, however to do this every time would be very impractical in my case.
I realize that I could call a function containing the loop, and then the function call would probably work, but again this feels quite impractical. So I guess it boils down to the following question.
The question
What is a practical way to run a loop whilst debugging VBA code in Excel?
There is actually a way for using loops or other multi-line statements in the Immediate Window - using a colon : to separate statements instead of a new line.
Full solution is described here.
Note that in the Immediate Window you also don't have to declare the variables using a Dim statement.
To summarize, your snippet would look something like this:
For i = 0 To 6: j=i: debug.Print i+j: Next i
I think I understand your question. You want to run a multi-line code block (i.e. the loop) in the Immediate Window. This throws errors because the Immediate Window is only intended for single lines of code.
I don't have any suggestions other than those you already mentioned. I'd recommend putting your test loop into a separate function and calling that from the Immediate Window:
Sub Test()
Dim i As Integer
Dim j As Integer
For i = 0 To 6
j=i ' Do something
Next i
End
Another option is to set several breakpoints. You can also run one line of code at a time with F8.
What is likely the preferred method (i.e., what most people actually do) is use the full power of the IDE, which includes the Immediate, Locals and Watch panes. You can change the value of most variables at runtime by direct assignment in the Immediate Pane (i=6 will do exactly what you think it should do). The IDE also allows you to set breakpoints, add watch conditions, step through code line-by-line using the F8, step through function or procedure calls using Shift+F8, stepping over (and back) through code using the mouse/cursor, and with a few exceptions, you can even add new variables during runtime.
I have always written my For-loops like this:
For foo = 1 to 10
' do something
Next
However, when I read code snippets online, people always do this:
For foo = 1 to 10
' do something
Next foo
I have not noticed any difference between the two, and I can't find any documentation on next statement is more desirable. What is the difference between those two (if any)?
The counter after the Next statement is optional. It used to be required in BASIC-derived languages, but this is no longer the case in VBA.
You can check the VBA reference:
If you omit counter in a Next statement, execution continues as if counter is included. If a Next statement is encountered before its corresponding For statement, an error occurs.
The reason people still add the counter it to increase readability.
It's for when you have multiple for loops.
For example,
For i to j
For k to l
next k
next i
Otherwise, the next is ambiguous. It's not absolutely necessary, as the loop will still work without it, but it's just good practice to have it marked for the sake of anyone else reading your code.
Something we can just put break point on while making sure it doesn't do anything else.
In c, that would be while(false);
What to do in vb.net?
If you always need it to break there you can put
Stop or Debugger.Break()
If you really want a No-Op for some reason (could this turn into a contest for the most ineffectual single line of code?!), how about these?
System.Threading.Thread.Sleep(1) - 1ms is unlikely to have a huge impact outside of a loop
Debug.Write("") - doesn't appear to output anything.
There is a legitimate use-case for this.
When a temporary breakpoint is required after the statement of interest and this is the last line inside an if statement, an extra no-op type statement is required to place the temporary breakpoint on.
In this case I use:
If someCondition >0 Then
doSomething
Space (1) 'Dummy line to place breakpoint
End If
This returns a string containing one space, but does not assign it to anything. I use it in VBA, but it's also supported in .net
My two cents...
You can combine any series of commands onto one line with colons:
If False Then : End If
Select Case False : Case Else : End Select
I've also made it into a sub. Then it gets a recognizable name of own:
'Definition...
Public Sub noop () 'Or Private, Protected, etc.
End Sub
'Usage...
Sub Main()
If sometest Then
noop
Else
MsgBox "test is false"
End If
End Sub
Very strange question, you could place a BreakPoint about anywhere in the code. But here are some useless lines :
Do While False
Loop
While False
End While
Even the following :
Dim hello = Nothing
Or this :
Format("", "")
A no-op statement is also useful as an aid to document code nicely and make it more easily understandable. You could for example put in a statement like A = A.
For example:
If MyNumber => 100 then A = A
Else:
I know this is an old query, but for what it is worth, my preferred solution to the original question is
Debug.Assert (vbTrue)
If you wanted, you could use a variable instead of vbTrue and then enable/disable all breakpoints in your code by changing one variable
Dim bDisableBreakpoints as Boolean: bDisableBreakpoints = vbTrue
'your code here
Debug.Assert (bDisableBreakpoints)
'rest of your code
Simply change bDisableBreakpoints to vbFalse and the breakpoints will be set wherever you have used Debug.Assert
My personal favorite is
dim b=1
Then I put a breakpoint there.