Develop Reference

How to make an object exist in the current context?

I fully understand why this is happening, but I don't know how to solve it as my attempts all didn't work.
I'm loading a file using MsgReader. I need to catch exceptions.
try
{
var message = MsgReader.Mime.Message.Load(fileInfo);
}
catch(IOException e)
{
MessageBox.Show(e.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
if (message.Attachments != null) //if has attachments
{
//...
This obviously fails as the object is created within the try. How can I instantiate the object but without having it load the file?
I've tried this before the try:
var message = new MsgReader.Mime.Message;
Error:
Severity Code Description Project File Line Suppression State
Error CS1526 A new expression requires an argument list or (), [], or {} after type
I've also tried variations of this, but I can't find the type I need to specify.

As the error states, if you want to create a new object then you need parentheses to invoke the constructor:
var message = new MsgReader.Mime.Message();
However, in this case it looks like you don't actually want a new instance, but just to declare the variable:
MsgReader.Mime.Message message = null;
In this case the declaration just needs an explicit type specified because var won't be able to infer the type from just null.
Just be aware that if the code in the try fails then message will be null and can't be used/dereferenced.
(And, of course, remove the var keyword when assigning a value to the variable within the try block.)

Error CS0103 when a variable is actually in the right scope

I have this control (db is the Entity Framework context):
if (db.Sites.Any(s => s.Name.Equals(name))) throw new NameAlreadyInUseException(name);
When I run my tests and debug it fails giving me the error:
Error CS0103: the name 's' does not exist in the current context.
I honestly can't get my head around it and Google hasn't really been helping... any help is appreciated, thanks in advance. Isn't s used correctly here? (I'm still learning, so maybe I missed something but my code here looks ok to me)
Edit:
the debugger triggers the error on this line and I am not using s in any other place other than inside that if statement. (I edited the line to show what happens with the if)
Edit2: complete code of the function
public void CreateSiteOnDb(string connectionString, string name, int timezone, int sessionExpirationTimeInSeconds,
double minimumBidIncrement)
{
CheckInput_CreateSiteOnDb(connectionString, name, timezone, sessionExpirationTimeInSeconds, minimumBidIncrement);
try
{
using (var db = new AuctionSiteContext(connectionString))
{
if (db.Sites.Any(s => s.Name.Equals(name))) throw new NameAlreadyInUseException(name);
var site = new Entities.Site
{
Name = name,
Timezone = timezone,
MinimumIncrement = minimumBidIncrement,
SessionExpirationInSeconds = sessionExpirationTimeInSeconds
};
db.Sites.Add(site);
db.SaveChanges();
}
}
catch(NameAlreadyInUseException)
{
throw;
}
catch(Exception)
{
throw new UnavailableDbException();
}
}
Edit3: Error as shown during debugging

It is not in the right scope.
In the screenshot you are in the scope of CreateSiteOnDb -> try -> using, but s does not belong to that context.
In very basic terms s => .... is converted to function of a class, and it is called from inside Any. so let's assume that our expression is function named Steve. Steve would look like this:
bool Steve(ISite s)
{
return s.Name.Equals(name);
}
this means s is the parameter of Steve, and is only valid inside Steve, which becomes CreateSiteOnDb -> try -> using -> Any -> Steve
So to see s you need to be in two more levels. Please, put your cursor inside the expression and then put a breakpoint.

Need to Write Data from CAPL to C# code and read back to CAPL script

I am using CANoe tool for CAPL scripting.
And I have referred this link for help given by Vector: https://vector.com/portal/medien/cmc/application_notes/AN-IND-1-011_Using_CANoe_NET_API.pdf
Now I am facing issue at step or section: 2.7 Calling CAPL Functions.
There are no syntax errors, but I think, the code is not able to retrieve the function from the CAPL file as it is giving this error when I pass values to the function from C# code.
Error statement:
An exception of type
'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in
System.Core.dll but was not handled in user code
Additional information: Cannot convert null to 'int' because it is a
non-nullable value type
If there is a handler for this exception, the program may be safely continued.
Can some one tell me what exactly the issue is?
Code:
public void Init()
{
CANoe.Application myApp;
myApp = new CANoe.Application();
CANoe.Measurement mymeasure;
mymeasure = (CANoe.Measurement)myApp.Measurement;
myApp.Open(#"D:\Planter CAPl\CANoeCAPLdll.cfg", true, true);
CANoe.OpenConfigurationResult ocresult = myApp.Configuration.OpenConfigurationResult;
if (ocresult.result == 0)
{
CANoe.CAPL CANoeCAPL = (CANoe.CAPL)myApp.CAPL;
CANoeCAPL.Compile(null);
CANoe.CAPLFunction mydata;
mydata = (CANoe.CAPLFunction)CANoeCAPL.GetFunction("Data");//CANoeCAPL.GetFunction("DataShare");
mymeasure.Start();
Thread.Sleep(2000);
int Result = (int)mydata.Call(10,20,30);// Exeception error is coming at this point*
if (mymeasure.Running)
{
mymeasure.Stop();
}
}
}

I think the error message is relatively self-explanatory, you're trying to convert a null value to an int type. Since int is a value type, it cannot be null, therefore, you get an exception.
In the line
int Result = (int)mydata.Call(10,20,30);
The value returned by mydata.Call(10,20,30) is null. You should check if that value is null and do something.
var myDataResult = mydata.Call(10,20,30);
if(myDataResult == null)
// do something
else
int result = (int)myDataResult;
As to why the call to the Call method returns null, you'll have to check the API you're using.

Visual Studio issue with recognising variables

Okay so in short:
I declare a variable, say
string str = "Random";
then I try to perform any sort of operation whatsoever, say
str.ToLower();
And neither visual studio, nor intellisense recognise it at all.
VS gives me the name "str" does not exist in the current context. This happened right after I installed xamarin but I'm not sure if it's related.
Also this issue would not occur if I was inside a method, just when I'm directly inside a class.
This is my code:
public class Program {
public void randomMethod() {
string str2 = "Random";
str.ToUpper(); //this line shows no errors
}
string str = "Random";
str.ToLower(); //this line does show the error
}
str would be underlined red and the warning mentioned above would appear.
Does anybody know what's going on?

you even point the issue out yourself
you cannot do this
public class Program {
string str = "Random";
str.ToLower(); //this line does show the error
}
when would you expect that code to run?
You must put executable code inside a function. You point out that this works.
I cannot propose a fix since I do not know what you are trying to do.

It is a scope issue:
public class Program {
public void randomMethod() { //method scope starts
string str2 = "Random";
str.ToUpper(); //this line shows no errors
} //method scope ends
string str = "Random"; //this is a class field, but is missing an accessibility level
str.ToLower(); //this line SHOULD show an error, because you can't do this in a class
}

Variable does not exist in current context and invalid arguments

I am trying to validate a text box.I have validated a couple of other text boxes and they work fine.This one has some error.
My code looks correct to me.Someone please point out my mistake and tell me why Visual Studio 2010 is prompting an error of invalid arguments and variable not in current context:

You need to define string errorMsg; in addTextBox_Validating function before you call ValidAddress.

You need to define the errorMsg variable before using it as an out parameter.
string errorMsg;

Read up on how to use out.
Although variables passed as an out arguments need not be initialized prior to being passed, the calling method is required to assign a value before the method returns.
class OutExample
{
static void Method(out int i)
{
i = 44;
}
static void Main()
{
int value;
Method(out value);
// value is now 44
}
}

You need to pass a string as second parameter to ValidAddress. Try and add
string errorMsg = null;
as first line of addTextBox_Validating()

You have not declared the errorMsg string.
private void addTextBox_Validating (object sender, CancelEventArgs e)
{
string errorMsg = "";
...etc
}
In ValidAddress, the errorMsg string is passed in to the function as a parameter, so this issue does not arise.

As far as I can see, errorMsg is not declared anywhere.
Try changing addTextBox_Validating by adding a declaration for it
e.g.
var errorMsg = string.Empty;
if (!ValidAddress(...
An out variable needs to be declared in the context that it is used.
hth
Alan.

Where is errorMsg defined? It looks like it's sent in as a parameter to ValidAddress, so addTextBox_Validating, being a different method entirely, doesn't have access to it, as errorMsg is scoped to only exist in ValidAddress. Long story short, you haven't initialised your variable.