I'm trying to write a while loop that tests whether an input is valid or not and it keeps asking if the user insists on the wrong input. If it is a valid one, the program just goes on. This is where i'm at.
while true
try
selected_row = readline()
selected_row = parse(Int8, selected_row)
break
catch e
if isa(e, LoadError)
#warn "type a valid number between [1,8]"
elseif isa(e, ArgumentError)
#warn "type a valid number between [1,8]"
end
end
end
println("you chose (C|R) ($selected_row)")
The problem is that when the input is correct I get an error.
LoadError: UndefVarError: selected_row not defined
The while loop creates a new scope. Now the way to fix the issue depends on where you put your code.
If it is inside e.g. a function then use:
local selected_row
before the loop (inside the function body) and things will work.
If your code is in top-level scope write:
global selected_row = parse(Int8, readline())
in your code which will guarantee that a global variable selected_row will be created.
Having said that I would recommend to write your code as follows:
function get_int8()
while true
selected_row = tryparse(Int8, readline())
isnothing(selected_row) || return selected_row
end
end
selected_row = get_int8()
Related
I am trying to filter an array in VBA by using the filter function. But every time I try to execute the code, I get an error message
Compile error:
Wrong number of arguments or invalid property assign
for some reason. I copied some code from an external source to test it out, but even the simplest example doesn't seem to work. Here's the code:
Private Sub Befehl0_Click()
Dim langs(5) As Variant
langs(0) = "English"
langs(1) = 375
langs(2) = "Spanish"
langs(3) = 442
langs(4) = "Chinese"
langs(5) = 1299.5
output_arr = Filter(langs, 375)
End Sub
Every time I execute the code, the function "Filter" gets highlighted. Does anyone know the answer to this problem?
It works if I try output_arr = VBA.Filter(langs, 375) as BigBen has stated in the comments!
My colleagues frown upon me because according to our sourcesafe, I added parentheses to the method-property thus resulting in a stackoverflow.
Since I'm sure I did no such thing on purpose, I wonder if somehow I used a obscure shortcut which performed these changes.
This kind of stuff :
Public Function Opslaan() As Boolean
If something_wrong() Then
opslaan = False
End If
If opslaan = False Then
Do_Something_Else()
End If
Return opslaan
End Function
and this got changed into :
Public Function Opslaan() As Boolean
If something_wrong() Then
opslaan = False
End If
If opslaan() = False Then '' See the parentheses here added automatically
Do_Something_Else()
end If
Return opslaan
End Function
Any help is appreciated.
This looks like bad old VB6 code converted to VB.NET.
The problem is VB6 allowed you to treat the current function name as a variable and update its value all throughout the method. Then, when you exited the method whatever value this variable had would be returned to the caller. This syntax is confusing and should never be used, even in VB6 since there is a better way.
Update all code you find like this to something like:
Public Function Opslaan() As Boolean
Dim result As Boolean = True
If something_wrong() Then
result = False
end if
If result = False Then
Do_Something_Else()
End If
Return result
End Function
This is much clearer code and will never mistakenly call the same routine.
Also, this is totally personal preference, but I prefer to not check booleans with equals statements. So If result = False Then becomes If Not result Then and If result = true Then becomes If result Then. That almost always feels cleaner to me for Booleans.
I have a an array in my module, so I want to display the contents of my array in a form textbox, here is my array
Module Module1
Sub AddCourse()
Dim Subjects() = {"Ms Office 2007", "internet and commmunications", "Lifetime skills"}
For i = 0 To UBound(Subjects) ' FOR LOOP TO WRITE AN ARRAY
i = i +1
Subjects(i)
Next
txtComputer.Text = subjects()
my problem is, when I try to use my texbox txtComputer in my module I get an error.
My question is, how do I make a form textbox to be used in a module
I get an error that reads "Error'txtComputer' is not declared. It may be inaccessible due to its protection level."
My question is based on, how do I get this error fixed?
There are several suggestions I have for you.
First, don't use UBound. That's an old VB6 function that is only provided for backwards compatability. You should instead use Subjects.Length.
Next, when you're incrementing the i variable, you don't need to say i = i + 1. You can just use the += operator for that (e.g. i += 1).
However, you shouldn't be explicitly incrementing i inside your For loop, anyway. The loop automatically increments the variable for you each time it iterates through the loop. If you do it explicitly yourself inside the loop, like that, it will skip every other item.
Next, in this case, you really should just use a For Each loop, rather than an iterator:
For Each subject As String in Subjects
'...
Next
Next, you aren't actually concatenating the items together inside you loop. You should be doing something like this:
For Each subject As String in Subjects
txtComputer.Text += subject
Next
However, in that case, for efficiency sake, you really ought to use a StringBuilder, like this:
Dim builder As New StringBuilder()
For Each subject As String in Subjects
builder.Append(subject)
Next
txtComputer.Text = builder.ToString()
But, all of this is moot because all you really need to do is to call String.Join:
txtComputer.Text = String.Join(", ", Subject)
As far as why you can't access the text box from the module, that is because the module is a separate object, so the text box is entirely out of scope. For instance, what if you had two instances of your form displayed at the same time? How in the world would this module know which form's text box you were referring to? The simplest way to correct that would be to pass a reference to your form into the module's method, like this:
Module Module1
Sub AddCourse(f As MyFormName)
f.txtComputer.Text = "Hello world"
End Sub
End Module
And then you could call it from the form, like this:
AddCourse(Me)
However, that would be exceptionally bad practice. Ideally, nothing outside of the form's code should ever deal directly with any of the controls on the form. So, the far better way to do it would be to simply have the method return the data, and then have the form set it's own control to the data that is returned, for instance:
Module Module1
Function GetCourse() As String
Return "Hello world"
End Function
End Module
And then call it from the form like this:
txtComputer.Text = GetCourse()
You can use String.Join to create a string which separates each subject with Environment.NewLine:
txtComputer.Text = String.Join(Environment.NewLine, Subjects)
The problem with your for loop is that it makes no sense at all since you have already declared and initialized the array in one line.
If you want to use a loop anyway, you can use a StringBuilder to concat all strings together:
Dim subjectBuilder = New System.Text.StringBuilder
For Each subject In Subjects
subjectBuilder.Append(subject).Append(Environment.NewLine)
Next
If subjectBuilder.Length <> 0 Then subjectBuilder.Length -= Environment.NewLine.Length
txtComputer.Text = subjectBuilder.ToString()
I have been looking through old code to get familiar with the system I use and found a piece of code that I feel can be used better.
What goes on here is some data gets added to the collection(around 150 string variables, some with two variables(variableName/VariableValue), most with only one(VariableName)). It will try to set a module level string variable to the item of the collection passing it the index(variableName) then if there's a value setting the VariableVAlue to the module level variable.
What I feel needs work is that if the collection is passed a variable and the variable doesn't have a value it will return a "" which would cause a runtime error hence there's a On Error GoTo Handler code to manually add a "" to the collection. I feel there's a better way to do this rather than knowing there will be a runtime issue then solving it after catching it. Would there be a way to have a return "" not throw an exception or would the use of an Array also work here since it's a "collection" as well?
Here's an example to try to help visualize:
Public Function GetCollectionVariable(ByVal varName as string) as String
If collection1 Is Nothing Then
m_collection1 = New Collection
End If
On Error GoTo Handler
GetCollectionVariable = collection1.Item(VarName)
exit function
Handler:
collection1.add("", VarName)
GetCollectionVariable = ""
End FUnction
Thanks for your time!!
If Collection1 is a dictionary, you can use TryGetValue.
Got a trouble in a VBA excel program.
Sub code(s)
...
code = t
End Sub
And then :
Sub CommandButton1_Click()
...
For i = 0 To size
current_y = code(string_array(i))
...
End Sub
When i run the program, i got this error "Variables are required" (not sure, i'm working on a japanese version of excel). Sub CommandButton1_Click is highlighted and code is selected inside CommandButton1_Click. Can't figure out why, though it must be simple...
You're trying to return a result from a Sub. Try declaring it as a function instead, as this is able to return values to the caller:
Function code(s)
...
code = t
End Function
If it makes it any clearer, on my English version the error message is:
Expected Function or variable
Does the code include Option Explicit? Perhaps the error translates to "Variable declaration required"? Try removing option explicit - if that fixes it remove that line, then go through checking all variables are declare (e.g. dim current_y as string).