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I'm just using :
this.myDataGrid.DataSource = myDataSet;
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this.myDataGrid.DataSource = myDataSet;
only the first datatable of the dataset will be assigned to the datagrid if we use the above syntax. But i have to use the datarelation of the dataset. what should do for that?
thanks a lot for your response.
thanks in advance
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Hi everyone, I'm trying to use a column from my database as a checkbox, any idea how to do it?? What's the retrieved value of it's checked/uncheced state?? is it numeral, textual, byte, boolean and how to get this value.. please help.
Note: I tried to customize a VARCHAR2(22) field from ORACLE and I keep getting this error:
Cannot set column 'MyCheckBoxColumn'. The value violates the MaxLength limit of this column.
Thanx a bunch guyz![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
Smile: A curve that can set a lot of things straight!
(\ /)
(O.o)
(><)
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I have used bit datatype in sql. So it would be 0 or 1 which seems to translate nicely to true and false which is what you need for a checkbox.
Hope that helps.
Ben
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kubben wrote: Hope that helps.
Thanks but no
Smile: A curve that can set a lot of things straight!
(\ /)
(O.o)
(><)
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Dear gurus,
I have the following problem.
After building my project, I want to copy in a "post-build-step" files from anywhere to my exe-directory. But I only want to copy if files are not present already or if files are newer.
Can anybody give me a hint how to perform this?
Thank you in advance
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Make your post build step a program that does exactly what you want.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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Hello All,
I want to show an animated gif one of the DataGridViewColoumns, but it shows like static image. Do you have any suggestion? Thanks...
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Can anybody pleae explain me , if possible with exmamples, the different purposes of using SyncRoot property and Synchronized methods?
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SyncRoot Property:
Gets an object that can be used to synchronize access to the collection.
public virtual object SyncRoot {get;}
Property Value:
An object that can be used to synchronize access to the collection.
Synchronized Methods:
Synchronisation plays an important role in multithreaded applications where the threads are not independent of each other and share common resources. This is because if two threads share common resources and try to manipulate the resources simultaneously, the resources become inconsistent. To tackle such situations synchronisation provides a lock on the resource that is shared among threads and makes a thread wait until the other thread finishes the job with the resource. Thus synchronisation ‘locks’ the shared resource and prevents another thread from using it.
C# provides a lock keyword to lock the shared object or resource. Whatever is written inside the parenthesis following the lock keyword gets locked for the current thread and no other thread is permitted to obtain the lock on that resource or object. We can write an expression that evaluates to an object, or just the object on which we wish to have a lock, inside the parenthesis. Whatever the expression may be, the result should be a reference type. The code that uses the object to be synchronised should be written inside the block of the lock statement.
To give you a more concrete example, consider two threads working on a file. If both the threads try to open the file and write to it simultaneously, an exception is thrown. Here what we need to do is synchronise both the threads in such a way that only one thread opens the file and writes in it at any given moment.
Regards,
Satips.
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Any code snippets please?
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Now if the user supplies some number in the textbox and clicks on the purchase button, the following handler gets called:
In this Sample Code
FileInfo f;
FileStream fs;
byte total=100;
f = new FileInfo ( “C:\\log.bin” );
Thread t = new Thread (new ThreadStart(checker));
t.IsBackground = true;
t.Start();
<br />
private void purchase_Click ( object sender, System.EventArgs e )<br />
{<br />
lock ( f )<br />
{<br />
try<br />
{<br />
fs = f.OpenWrite( ) ;<br />
byte b = byte.Parse ( quantity.Text ) ;<br />
total = ( byte ) ( total - b ) ; <br />
fs.WriteByte ( total ) ;<br />
MessageBox.Show ( "Transaction Complete" + "\n" + "Item <br />
remaining: " + total ) ;<br />
fs.Close( ) ;<br />
}<br />
catch<br />
{<br />
MessageBox.Show ( "Cannot Open file" ) ;<br />
}<br />
}<br />
}<br />
Regards,
Satips.
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Synchronized returns a collection that locks on each call, i.e. while you call a method or property, no other thread may modify the collection. This is convenient, but not enough.
Imagine the following code snippet:
if (myList.Count > 0)
myList.RemoveAt(0);
In this case, you have two separate calls (querying "Count" and removing an object). However, between the calls, some other thread may access the list and e.g. clear it completely. In this case, RemoveAt will fail.
For that scenario, you get the SyncRoot:
lock(myList.SyncRoot)
{
if (myList.Count > 0)
myList.RemoveAt(0);
}
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Thanks Peter, But still i am not clear.
First point is, if we synchronize the whole method, how other thread can make calls between Count and RemoveAt?
Secondly, instead of lock(mylist.syncRoot) can't we specify lock(mylist)?
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kumar.bs wrote: if we synchronize the whole method, how other thread can make calls between Count and RemoveAt?
They can't (as long as they use the lock), and that's the whole point. because between "Count" and "RemoveAt" noone may modify the list.
Keep in mind that querying Count is usually very fast, so lock acquisition and RemoveAt will take the majority of execution time anyway.
kumar.bs wrote: lock(mylist.syncRoot) can't we specify lock(mylist)?
Two problems:
First, "List Proxies". The synchronization works correct only if all threads accessing the list use the same object to lock on. However, the List interface might not hold the data itself, but expose the interface for some underlying data. If one thread lokcs on the list proxy, and another thread locks on the underlying data, we have the concurrent access we need to avoid.
Second, Lock Order.
There is a problem wiht locking on publicly visible symbols. When you have two locking objects A and B, one thread might lock in the order A, B the other in order B,A. This leads to a deadlock situation that cannot be solved.
That's why locking on public objects is almost always a bad idea. You need to be very clear which lock objects exsit in your code (and the code you call!), and give them a definite order. SyncRoot helps here a little bit since it is a dedicated object used for locking, that is provided by the underlying data.
helped? 
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Thanks Peter, could able to understand better.
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Hi frenz,
In my application im changing formats of images...so while the process is going on i want to show the names of the images being processed in the status bar...for that i have the code...but the prob is...the for is not getting refreshed...i mean the names are not getting updated in the status bar...only the firat image's wis shown in the bar and if any messagebox pops up in between then the status bar gets updated with the latest images name...
i want to make the form get refreshed evry time the name is changed so tht the status bar gets updated with the name...
Plz help in this...
P.S writing code in C# 2005
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You should move the process to another thread, so your UI updates. Application.DoEvents() is the cheats way to try and avoid writing threaded code, you can try that first, perhaps
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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thank u for the quick reply...can u tell me in a bit detail way how to go about that...
thanx in advance...
Inder..
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The right way ? You need to read up on the BackgroundWorker class, have it do whatever your app is doing, and use the progress notifications to communicate with your main thread and update your UI.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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I want to check whether the text entered in a control, say a text box is of double or not.
How can I do it? Thanks.
Keshav Kamat
India
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Use double.TryParse(text).
Deja View - the feeling that you've seen this post before.
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I want to store more than one doc file, pdf file ,ppt file
,other file using single id.
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I have no idea what your question is
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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Do you need to convert a file into all these types that you mention?
You are being very vague and/or not making much sense.
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