put bellow lines before your class funtion and after your class function called.
In your function in class i thing u create new tree view control and return the same. In this case parent control + location + size does not exist. After that when you assign to your control it behaves like it has no parent.
1) pass tree view of the form in to class function
I have a datagrid bound to a dataview. I created some functionality to add new rows and delete rows. When I delete an row and click on the save button to save to the database I get the following message:
"Deleted row information cannot be accessed through the row".
And the delete obviously fails. Anyone with ideas on this?
i implemented a virtual listview component making use of "LVS_OWNERDATA"-style in C#; everything works fine so far, but if the component looses focus and gets it again, you will get an "ArgumentOutOfRange"-exception caused by "FocusedItem"-method...
i tried to override the method, but this certainly not works, the implementation takes always the original method code...
The issue is:
You are given an array of integers of size n containing values in the range 1 to n-1. Obviously there’s at least one duplicate value in this array. Please let me know the algorithm for finding one such duplicate value.
There are many ways you can go about doing this. There are a few questions you should look at first though. Is the array sorted? Can you define another data structure? Are you trying to keep the complexity below a certain level?
I might do something like the following:
for (int iSize = 0; iSize < yourArray.Count; iSize++)<br />
while (yourArray[iSize] != iSize)<br />
if (yourArray[iSize] == yourArray[yourArray[iSize]])<br />
MessageBox.Show( "Duplicate value of " + yourArray[iSize].ToString() );<br />
iSize = yourArray.Count;<br />
Swap(yourArray[iSize], yourArray[yourArray[iSize]]);<br />
I didn't really test this, just pulled it off the top of my head real quick. It might work, but I can't give any guarantees.
I have a tabcontrol with 3 tabs, and each tab has its own ListBox control.
I populate the listbox controls from a dataset i retreive from a database. Everything here is fine.
The problem comes when the data is displayed. The ListBox does contain a collection, and all the items are selectable, BUT they are invisible.
Every item in the listbox remains Invisible until I do the following:
- Move the form (by dragging with the mouse)
- Change the tab (redraws the listbox control)
Once I do that, the listbox items are viewable.
Can anyone give me any insight as to what is happening here?
Can anyone suggest the easiest way to scan a photo from a c# application ... is the Windows Image Acquistion Automation Layer the way to go? or should I purchase a third party control such as what AtalaSoft, LeadTools or PegasusImaging provides? ... does anyone have any experience any of with these tools?
I need my C# app to tell any scanner to scan the current image ideally into its raw image format (so no image correction is applied) and it all needs to be from managed code.
well, a very good question... i'm relatively new to c# programming, too, and wondered also what they can do for me...
well, interfaces look like classes, except (see C# in a nutshell):
- the don't deliver implementations to their members, but a specification; so they are in some parts identical to abstract classes
- one class/structure can implement more than one interface, but one class can only derive from one base class
- a struct can implement an interface, but can not derive from a base class
the clue is, to define basic operations that every derived class/struct has to implement; the implementation itself may look different, but the aim of the called operations has to be the same...
let's say you implement a webshop; you know three different account types: a paypal account, a bank account and a credit card account; all types use different properties to describe the account; however, all derive from interface "IPaymentTransferAccount"
when your customer buys something from you, all have to implement a method called "GetMoneyFrom(float bucksCount, Currency currency)" - each of them has its own implementation of initializing the money transfer, but in your code, you only call "IPaymentTransferAccount account = Customer.Account; account.GetMoneyFrom(price, Currency.USD);"
finally, you need no "dummy"-implementation in a base class, but each of it can implement many other interfaces where appropriate, that's it.
An interface ensures that when something wants to invoke methods on a class implementing the interface, that those methods exist and have a particular signature. It's like a contract. If you inherit from an interface, your class is saying "I'm implementing the methods that are defined in the interface, so anyone who knows about the interface can use my methods."
Wow i think i understand them now! So interfaces were made solely to make sure people deriving from a class followed the same naming conventions and provided for the same functionality in their classes?
Here's a test program i wrote that helped me out:
#region Using directives
FocusedWolf wrote: So interfaces were made solely to make sure people deriving from a class followed the same naming conventions and provided for the same functionality in their classes?
That's 1/2 of it. The other half is that someone that USES the interface is guaranteed that a class (which can be totally unknown) derived from the interface actually implements the methods in the interface.
In your example (and it's customary to prefix a class name with an "I" if it's an interface, so Wolf would be IWolf), your main would look more like this:
class Program // don't need to derive from anything here
IWolf awolf = Factory.MakeWolf();
Console.Write("What color is the wolf that's chewing on you? ");
awolf.Fur = Console.ReadLine();
Console.Write("How many teeth does it have? ");
awolf.Teeth = Console.ReadLine();
Now, Factory.MakeWolf() is a static method that maybe looks at some configuration information somewhere and either returns an instance of WereWolf or RegularWolf. The point is, the Main() program doesn't care which--it assigns the instance to the interface that all specialized Wolf classes implement. It can then call methods on those instances because the interface says that they must exist.
Another reason for interfaces is that C# doesn't support multiple inheritance, but you CAN specify multiple interfaces, which is sometimes a useful way of having one specialized class that implements several different interfaces.