String^ exportedFunctions = textBoxFunctions->Text.Split("\n");
I get an error:
Expression must have class type
Why is it everytime I search for a solution to a problem I get answers without the :: or -> notation?
Like if I google for c# get winform value I get an answer along the lines of:
winformElement.Value
But it won't work unless I actually type:
winformElement->Value
My Project is a CLR project with the WYSIWYG winform editor.
I found the answer here.
array<String^>^ mySplitString = myString->Split('\n');
Related
I'm trying to use Excel-DNA to integrate my VB.NET DLL into VBA. But I'm running into the following problem. If I try to add this line before one of my static (Shared) class functions:
<ExcelFunction(Description = "Do stuff", Category = "Useful functions")> _
I get a compile error saying "Name 'Description' is not declared" (and same for Category). I've got VS2005 so maybe that has something to do with it. The example given in the Excel-DNA documentation is for C# and I'm feeling that maybe I just need to get the syntax right.
I've got the needed
Imports ExcelDna.Integration
line at the beginning of my file.
The syntax for using attributes in VB.NET is a bit different to C#. You need to write the property assignments with ":=", something like this:
<ExcelFunction(Description:="Do Stuff", Category:="Useful functions")>_
...
I have a simple code in C#:
Console.WriteLine(string.Join<char>("", ""));
And I can't convert it to VB.Net. Even reflector show me code in VB like:
Console.WriteLine(String.Join(Of Char)("", ""))
But it can't be compiled becouse I have an starge error:
Error 1 Expression expected.
It looks like VB.Net don't have this generic method at all.
Both project use Net Framework 4.
Why this error happened?
UPD:
I've create a custom class and copy Join(Of T) declaration to it:
Class string2
Public Shared Function Join(Of T)(ByVal separator As String, ByVal values As System.Collections.Generic.IEnumerable(Of T)) As String
Return "1"
End Function
End Class
Console.WriteLine(string2.Join(Of Char)("", ""))
It works
UPD2:
My compilation string, where you can see that I'm using Net4:
http://pastebin.com/TYgS3Ys3
Do you have a code element named String somewhere in your project?
Based on the answer you have added to this question (where you indicate that changing String to [String] appears to have solved the problem), I guessed that this may be the result of a naming collision.
I was able to duplicate the error you are seeing -- "Expression expected" -- by adding a module to my project called String and defining a (non-generic) Join method from within that module.
This may not be the specific scenario you find yourself in. But the fact that the code works for you with [String] is, to me, very compelling evidence of a simple namespace collision.
Based on the documentation for the "Expression expected" error, I'm guessing you haven't included the entire section of code where this error is appearing for you.
Do you have a lingering operator such as + or = somewhere?
(The VB.NET code you posted is indeed equivalent to the C# code above it and should compile no problem. This is why I suspect the real issue lies elsewhere.)
String.Join<T>(string, IEnumerable<T>) is useful with LINQ, for standard joins is better to use the String.Join(string, string()) overload.
In C#, "" as Char produces an empty Char (\0). Writing the same thing ("") in VB produces an empty string which is not the same as an empty char. In order to produce an empty character, you'll have to write New Char().
Your VB code therefore becomes:
Console.WriteLine(String.Join(Of Char)(New Char(), New Char()))
Edit
I just checked and it appears String.Join does not support the format you're specifying.
Instead, it goes as follows:
Join(separator As String, value As String()) As String
Your code should be as follows:
Console.WriteLine(String.Join("", New String() {""}))
String.Join(Of Char)(str1, str2) wasn't added til .net 4, it seems. That's why your custom class worked -- it had the declaration, but the String class in the framework you're actually using doesn't.
Check your settings and references to make sure you're targeting .net 4 all around -- cause that's the only thing that seems able at this point to stop the call from working.
Here the solution:
Console.WriteLine([String].Join(Of Char)("", ""))
Why this problem occurs only with generic method? I wish I know...
I need to test a logical expression held in a string to see if it evaluate to TRUE or FALSE.(the strig is built dynamically)
For example the resulting string may contain "'dog'<'cat' OR (1>4 AND 4<6)". There are no variables in the string, it will logically evaluate. It will only contain simple operators = > < >< >= <= and AND , OR and Open and Close Brackets, string constants and numbers. (converted to correct syntax && || etc.)
I currently acheive this by creating a jscipt function and compiling it into a .dll. I then reference the .dll in my VB.NET project.
class ExpressionEvaluator
{
function Evaluate(Expression : String)
{
return eval(Expression);
}
}
Is there a simpler method using built in .NET functions or Lamdba expressions.
I tried the demo out for this project and you might like it over you current method of evaluating. Note, it doesn't use lamdba expressions or any build it .NET methods.
http://web1.codeproject.com/KB/vb/expression_evaluator.aspx?msg=1151870
try out: http://www.codeproject.com/KB/cs/ExpressionEval.aspx
More guidance :http://www.thefreakparade.com/2008/07/evaluating-expressions-at-runtime-in-net-c/
Good one: http://flee.codeplex.com/
Boolean Example which you are looking for : http://flee.codeplex.com/wikipage?title=BooleanExpression&referringTitle=Examples (ignore the variable adding part as you are not looking for variable)
Im trying to use the ComAutomationFactory class in VB .NET the example im working from is c# and is working fine but my project doesnt compile and says this class is not defined??
also what is the return type? in the c# example it returns a type of dynamic but this type does not exist in vb .NET?
Possibly you're sample is old, according to this blog:
http://silverlight-essentials.blogspot.com/2010/03/breaking-changes-in-com-interop-between.html
It's changed name as:
The class ComAutomationFactory has been renamed to AutomationFactory.
Additionally you have to reference System.Runtime.InteropServices.Automation for this class.
Regarding the return type, the answer to this question has a solution:
Iterating over Word Document Fields using ComAutomationFactory in Silverlight 4
Using VB.net, the following snippet gives the error below.
Dim _account = Account.Find(Function(x As Account) x.AccountName = txtFilterAccountName.Text)
or similarly if I do
.SingleOrDefault (Function(x As Account) x.AccountName = txtFilterAccountName.Text)
will both give the error "The method 'CompareString' is not supported". If I make the same call searching for an integer (ID field) it works fine.
.SingleOrDefault (Function(x As Account) x.Id = 12)
So integer matching is fine but strings don't work Is this a problem with the VB.net templates?
No this is not a problem with Vb.Net templates.
The problem is that you are not using a normal LINQ provider. Based on your tag (subsonic) I'm guessing you're using a LINQ to SQL query.
The problem is that under the hood, this is trying to turn your code into an expression tree which is then translated into an SQL like query. Your project settings are turning your string comparison into a call in the VB runtime. Specifically, Microsoft.VisualBasic.CompilerServices.Operators.CompareString.
The LINQ2SQL generater in question or VB compiler (can't remember where this check is done off the top of my head) does not understand how to translate this to an equivalent bit of SQL. Hence it generates an error. You need to use a string comparison function which is supported by LINQ2SQL.
EDIT Update
It looks like the CompareString operator should be supported in the Linq2SQL case. Does subsonic have a different provider which does not support this translation?
http://msdn.microsoft.com/en-us/library/bb399342.aspx
The problem is with SubSonic3's SQL generator and the expression tree generated from VB.NET.
VB.NET generates a different expression tree as noted by JaredPar and SubSonic3 doesn't account for it - see Issue 66.
I have implemented the fix as described but it has yet to merge into the main branch of SubSonic3.
BlackMael's fix has been committed:
http://github.com/subsonic/SubSonic-3.0/commit/d25c8a730a9971656e6d3c3d17ce9ca393655f50
The fix solved my issue which was similar to John Granade's above.
Thanks to all involved.