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The .NET P/Invoke marshaller has special knowledge about some types.
For example when passing a String, it passes the pointer to the string data, not the pointer to the managed string object.
When passing a StringBuilder, the .NET marshaller passes a pointer to the StringBuilder's internal buffer.
Another useful idiom is the SafeHandle: you can create your own SafeHandle-derived class and directly use that in P/Invoke signatures. The .NET marshaller will pass the underlying handle (IntPtr) instead. This is extremely useful because it avoids a number of problems: for example the finalizer could run when there are no active references to your object, but the underlying handle is still being used in a P/Invoke call. Using a SafeHandle directly in the P/Invoke signature makes the GC aware that the handle is used during the lifetime of the P/Invoke call, and it'll avoid finalizing the object until the call is complete.
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When passing a StringBuilder, the .NET marshaller passes a pointer to the StringBuilder's internal buffer.
This is the voodoo that had me baffled the most. To the .NET developer, the StringBuilder is a sophisticated managed class, but somehow the API is able to treat is like a char* (I think).
Thank you!
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Hi,
I am in need of customizable menu,where user can change the parent and child menu at any time in a UI.Also he can grant or revoke permission for a menus or sub-menu based on user group.
Need some url ,,,,,
Thanks
Guhananth.S
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You should start here[^]. In the top 10 is a CodeProject article, I suggest you read it. And some of the others as well.
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I need to read the Comments, Keywords (Description) in the metadata of a JPG file and then be able to write a modified comment. This is proving tricky and help would be appreciated. This metadata is that which appears when the image is right-clicked and these tags can be changed there.
What I am after is to be able to edit EXIF in JPG images, but I cant find any information in VB.
modified on Monday, August 9, 2010 8:28 AM
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I have an updatepanel with 3 dropdownlist and the selected item from the 1st one binds the 2nd, the selected item from the 2nd binds the 3rd and so on. For example you select a state and then the 2nd ddl has the list of cities in that state.
Well when a state is selected, the 2nd shows all the cities but the problem is that I can not select another city. The first on will always be selected and cb2_SelectedIndexChanged doesnt fire.
Thanks,
Martin
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" >
<ContentTemplate>
<asp:DropDownList ID="cb1" runat="server" AutoPostBack="true" />
<asp:DropDownList ID="cb2" runat="server" AutoPostBack="true" />
<asp:DropDownList ID="cb3" runat="server" AutoPostBack="true" />
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="cb1" EventName="SelectedIndexChanged" />
</Triggers>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="cb2" EventName="SelectedIndexChanged" />
</Triggers>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="cb3" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>
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Don't use multiple Triggers tags. If that isn't the source of your problem it is as least making it tougher to read your code. And if these dropdowns are the only things in the UpdatePanel you should consider just settings ChildrenAsTriggers and not even bother with the individual ASyncPostBackTrigger elements.
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<quote>*Contents of removed message*
i created mysqldump application using C#. it is saving to some path which i given. but how to make that application to save automatically like every 3 or 4 hours daily. i written code like below
public void Dump()
{
try
{
DateTime Time = DateTime.Now;
int year = Time.Year;
int month = Time.Month;
int day = Time.Day;
int hour = Time.Hour;
int minute = Time.Minute;
int second = Time.Second;
int millisecond = Time.Millisecond;
string path;
path = "E:\\BackupMysql1\\" + year + "-" + month + "-" + day + "-" + hour + "-" + minute + "-" + second + "-" + millisecond + "_temple.sql";
StreamWriter file = new StreamWriter(path);
ProcessStartInfo psi = new ProcessStartInfo();
psi.FileName = @"C:\Program Files\MySQL\MySQL Server 5.0\bin\mysqldump";
psi.RedirectStandardInput = false;
psi.RedirectStandardOutput = true;
psi.Arguments = string.Format(@"-u{0} -p{1} -h{2} {3}", "xyz", "abcd", "localhost", "database");
psi.UseShellExecute = false;
Process process = Process.Start(psi);
string output;
output = process.StandardOutput.ReadToEnd();
file.WriteLine(output);
process.WaitForExit();
file.Close();
process.Close();
}
catch (IOException ex)
{
MessageBox.Show("Error , unable to backup!");
}
}
anybody knows please reply me.
*End*
The easy way to do this is to use a scheduled job in the windows scheduler that is set to run at a set interval. Don't muck about attempting to write code to do this when the OS provides a perfectly serviceable method.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
modified on Friday, August 13, 2010 12:24 PM
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Hello,
I have a special requirement where I need to show grouped data in expandable form. For eg:
Order Date Total Amt
+ 1 05/06/2010 100.00
Item Qty Rate Amt
A 5 10 50.00
B 2 25 50.00
This format we normally see in Access when the data is grouped or a primary key of table A is the foreign key of table B. If I clikc "+" sign next to order #, I get to see the item details belonging to that order. If the order is already expanded "-" sign lies and if their are no item details pertaining to any order their should be no sign.
I know I can do this format using Tree, but that looks too off profesional.
Can you suggest me any idea to implement this using Vb.NET.
Thanks,
Thanks & Regards,
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Thanks.
But I need it for VB.NET application and not a web application. It doesn't seem that I can use this component in Vb.NET desktop application. Any idea or suggestions are welcome.
Thanks & Regards,
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Perhaps you should have specified the technology was Windows not Web.
There are plenty of examples here. Like this one, Collapsible Panels in VB.NET[^]
All Time Programming wrote: I need it for VB.NET
Not every example will be in VB.NET and you should learn to read and understand other languages and how to translate it to your needs.
I know the language. I've read a book. - _Madmatt
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Thanks alot, Mark. 
Your links answered my query much better. Thanks once again.
Yes Mark, I can read and translate from any to any among C#, VB, Java. But needed some guideline for start up also.
Thanks & Regards,
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Hi,
Is it possible to compare two excel sheets ie column names in each sheet by using SSIS package?
Need some urls or some examples
Notify user when there is no matching in column names and exlude that file and pick the next excel file placed in server.mappath.
Thanks
Guhananth.S
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Stop posting and read the guidelines
I know the language. I've read a book. - _Madmatt
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Hi,
In SSIS is possible to check
a) Excel template check ie comparing the column names of each sheet with another standard sheet
The SSIS must check if the uploaded excel is matching the standard excel.
b)The SSIS must pick any excel sheet placed in server.mappath ie able to pick any excel file names.
c)Also the SSIS must read the excel sheets and port data to respective tables.
How to do?
How to do these tasks in SSIS package.
If we deploy this,will the package check excek sheet format and notify admin,if any things goes wrong.
Thanks
S.Guhananth
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Please read the guidelines[^] and don't use capitals for your entire message. Also please clarify what your quesstion has to do with the .NET framework.
It's time for a new signature.
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HI,
How to create SSIS package in VS 2010
which option we need to choose
guhananth.S
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You cannot create an SSIS package in VS 2010. The installation of SQL Server 2008 can install the Business Intelligence Development Studio (BIDS) which is a variant of VS 2008. BIDS provides the templates and capability of creating and deploying SSIS packages
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