|
|
Do you actually need ref? DataRow being a class isnt it passed in by reference in any case?
|
|
|
|
|
Why have you changed the param to an out? That wasn't there in your original post!
|
|
|
|
|
That's true, it wasn't. My original post was a quick and dirty bit done from memory, and therefore incomplete.
Are you saying that ref or out is not required here at all? I can pass a DataRow and modify it to my heart's content?
I did test out "ref" when "out" failed, and that does work. Still not sure why "out" doesn't work in the "if (dr == null) case, but it's not clear to me what "unassigned" means here when the caller has already assigned a value to the variable...
|
|
|
|
|
the ref keyword forces the argument to be passed by reference, it has no effect on reference types such as DataRow, but consider the following example with a value type:
static void Main()
{
int i = 1;
NoRef(i);
Console.WriteLine(i);
WithRef(ref i);
Console.WriteLine(i);
}
static void NoRef(int i)
{
i = i +1;
}
static void WithRef(ref int i)
{
i = i + 1;
}
as for the out keyword, this means that the method itself has to set the value of the param before using it. Hence why you cant check it for null before initializing it to some value.
static void Main()
{
int i = 0;
SetOut(out i);
Console.WriteLine(i);
}
static vouid SetOut(out int i)
{
i = 1;
}
So to cut a long story short, just remove the out/ref keyword altogether from your method. You can still change the values of your DataRow within your method.
|
|
|
|
|
Hello,
I want to develop small application for Desktop Sharing if you provide me any example or any link will be good for me.
Thanks
Best Regards,
Chetan Patel
|
|
|
|
|
Look at the source code of VNC, I am sure that will scare you off, as this is no small feat.
|
|
|
|
|
i planning to create a web base vb script editor by c#
but i have no idea about this....
have any suggestion how to create it??
can i apply msscript.ocx for this editor?
|
|
|
|
|
how to insert float value from string into sql from C# .net in float column in database. It should accept only the given decimal point.
Ashok
|
|
|
|
|
Hello Ashok,
If I get it correctly, you wish to retrieve a value from a string variable
containing a floating value. If thats the case, you can try this.
String str = "123.32";
float f = float.Parse(str);
I hope this helps.
Regards,
Allen
Allen Smith
ComponentOne LLC
www.componentone.com
|
|
|
|
|
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
namespace TestApplication
{
public partial class Form1 : Form
{
progress prg = new progress();// this is a form
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Thread t = new Thread(new ThreadStart(loop));
t.Start();
}
public void loop()
{
showProgress();
for (long i = 0; i < 500000000; i++)
{
}
this.BeginInvoke(new MethodInvoker(showC));
}
public void showProgress()
{
//if (this.InvokeRequired)
{
this.BeginInvoke(new MethodInvoker(showP));
}
}
public void showP()
{
prg.ShowDialog();
}
public void showC()
{
prg.Close();
}
}
}
|
|
|
|
|
You need to show the progress window until the "Loop" finishes, right ? Then your code is wrong. prg.ShowDialog() in the "Loop" method blocks the current thread, which means your loop won't get executed until the progress closes.
Show the progress from the main thread and execute the "Loop" method in the thread which you created. Something like
private void button1_Click(object sender, EventArgs e) {
progress prg = new progress();
Thread t = new Thread(new ParameterizedThreadStart(loop));
t.Start(prg);
prg.ShowDialog();
}
delegate void ProgressCloseInvoker(progress prg);
public void loop(object obj) {
progress prg = obj as progress;
for (long i = 0; i < 500000000; i++) {
}
this.BeginInvoke(new ProgressCloseInvoker(CloseProgress), prg);
}
public void CloseProgress(progress prg) {
prg.Close();
}
|
|
|
|
|
N a v a n e e t h wrote: prg.ShowDialog() in the "Loop" method blocks the current thread, which means your loop won't get executed until the progress closes.
Not really, the OP is using BeginInvoke, which pushes the delegate to the UI thread and returns immediately.
|
|
|
|
|
S. Senthil Kumar wrote: the OP is using BeginInvoke
Ohh I didn't noticed that. Thanks for pointing it
|
|
|
|
|
Senthil, i have read you article and then implemented this program
http://www.codeproject.com/KB/cpp/begininvoke.aspx[^]
But what does the exactly invokerequired() do does it checks whether message is posted in message queue if it is posted then it returns true or false.
Clear me
|
|
|
|
|
I didn't noticed BeginInvoke on your sample, your code is correct then. As you are showing the progress as modal, there is no chance of clicking the button for one more thread to create. So there won't be any thread safety issues, AFAIK.
|
|
|
|
|
Senthil, i have read you article and then implemented this program
http://www.codeproject.com/KB/cpp/begininvoke.aspx[^]
But what does the exactly invokerequired() do does it checks whether message is posted in message queue if it is posted then it returns true or false.
Clear me
modified on Monday, July 21, 2008 3:57 AM
|
|
|
|
|
Mogaambo wrote: But what does the exactly invokerequired
InvokeRequired checks whether the current thread is the thread that created the control on which InvokeRequired is being called.
|
|
|
|
|
ok then y it gives 1 time true then false according to your program, it should always give false value as this thread doesn't created it.
|
|
|
|
|
If you looked at the code carefully, you would have noticed that the if (InvokeRequired) block actually passes the current method as the parameter to Invoke/BeginInvoke. The current method will therefore get called again, but this time on the UI thread, as it was passed as the delegate to Invoke/BeginInvoke, and InvokeRequired will therefore return false.
|
|
|
|
|
but this time on the UI thread 
|
|
|
|
|
You do understand what Invoke or BeginInvoke does, don't you? They help you execute the delegate, that you pass as the parameter, on the UI thread. Invoke will wait until the delegate completes, BeginInvoke simply posts it to the UI message queue and returns.
Either way, the UI thread executes the delegate - this is the "second time" that you are talking about. InvokeRequired will obviously be false, since it's the UI thread that created the control on which InvokeRequired is called.
|
|
|
|
|
Hello everyone,
I am writing an Http client. Any samples for dealing with Http authentication? e.g. https, certificate?
thanks in advance,
George
|
|
|
|
|
George_George wrote: Http authentication
I hopr you are using HttpWebRequest class. You can set the credentials to Credentials[^] property. Something like
HttpWebRequest request = WebRequest.Create(new Uri("http://somewebsite.com"));
request.Credentials = new NetworkCredential("username", "password");
|
|
|
|
|
Thanks N a v a n e e t h,
Your sample contains information about how to apply user name and password as authentication information. And also how to use the default certificate.
My question is, if the web site has some customized certificate, or the end user (e.g. my Http client) has some customized certificate, are there any samples about how to deal with it?
regards,
George
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
