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I have dynamically created textboxes in a loop, and given them names at creation time.
txtProdName.Name = "txtProdName" + i;
pn.Controls.Add(txtProdName);
txtProdDesc.Name = "txtProdDesc" + i;
pn.Controls.Add(txtProdDesc);
The above snippet works fine. Controls are created, and removed as needed.
Now, I would like to go back and read or write information into these textboxes, but I'm at a lost as to how to address them.
I'm trying to do something like:
txtProdName + i.Text = "Blah";
txtProdDesc + i.Text = "Blah2";
Now I know the above code won't work, but wondering if there is someway to do something similar? Or am I totally barking up the wrong tree.
Thanks in advance.
P.S. I haven't found an answer to this anywhere, which leads me to believe I'm at the wrong tree. 
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There are several ways to do that - but the easiest is probably to use Controls.Find:
TextBox tbProd = (TextBox)pn.Controls.Find("txtProdName" + i, false).FirstOrDefault();
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Ok, so I follow what you did with the code. Having difficulty in taking it to the next step.
My thoughts are, I should now be able to:
tbProd.Text = "Blah";
However, I get the following error:
'System.NullReferenceException'in Project.exe ("Object reference not set to an instance of an object.")
And to make sure I really do understand what you suggested:
TextBox tbProd = (TextBox)pn.Controls.Find("txtProdName" + i, false).FirstOrDefault();
Creating a new instance of a textbox, called tbProd that is being set to the first control found in the panel, pn with a name of txtProdName + i, and casting that to type textbox.
If I truly understand your code, and the error, it would appear that tbProd didn't actually get the copy I thought it did??
I truly want to thank you for your help.
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The FirstOrDefault method returns null if the collection of objects returned by Find has no elements: so use the debugger to look at the Panel.Controls collection and see exactly what it contains - I suspect that it doesn't have anything, in which case you need to look at the environment in which you are calling Find. When are you doing it, what else have you done, that kind of thing. We can't do that for you - we don't have access to your code!
And BTW:
TextBox tbProd = .... Doesn't create a new instance - it creates a variable that can reference an instance. It's a small but very, very important distinction!
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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The WinForms ControlCollection does allow you to use a string Key to access members:
pn.Controls["txtProdName3"].Text = "hello"; When you set the 'Name property of a WinForm Control, you have created the Key (why MS documentation calls it a 'Key baffles me).
So, that is a way you could access the run-time created TextBoxes without keeping a direct reference to them in some data structure.
However, I strongly advise you not to rely on that, and suggest you do something like this:
public List<TextBox> ListOfTextBoxes = new List<TextBox>();
public void createTextBoxes(int howMany)
{
TextBox txtProdName;
TextBox txtProdDesc;
for(int i = 0; i < howMany; i++)
{
txtProdName = new TextBox();
txtProdDesc = new TextBox();
ListOfTextBoxes.Add(txtProdName);
ListOfTextBoxes.Add(txtProdDesc);
txtProdName.Name = "txtProdName " + i;
pn.Controls.Add(txtProdName);
txtProdDesc.Name = "txtProdDesc " + i;
pn.Controls.Add(txtProdDesc);
}
}
ListOfTextBoxes[2].Text = "blah";
pn.Controls["txtProdName3"].Text = "hello";
string tbContent1 = ListOfTextBoxes[0].Text;But, if you are going to use the Index to access the TextBoxes, you can see immediately that you'll have to remember which index to use for TextBoxes that are 'txtProdDesc, and which to use for 'txtProdName.
To make the code clearer, I would use two separate Lists. I would also consider using two Dictionaries of Type <string, TextBox>
If the two TextBoxes are designed to function as a "pair;" I'd consider another data structure, or consider creating a custom UserControl ... all depends on your Application and its scope, purpose, run-time load, etc.
«I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center» Kurt Vonnegut.
modified 15-Oct-15 14:53pm.
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Gentlemen,
I wanted to thank you for your help. Both of you got me going again.
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I have a project that I have on TFS online. When Im trying to build the project, I get the following error:
Severity Code Description Project File Line Error The "Microsoft.CodeAnalysis.BuildTasks.Csc" task could not be loaded from the assembly C:\Users\Bryan\Source\Workspaces\TestProject\ContosoUniversity\packages\Microsoft.Net.Compilers.1.0.0\build..\tools\Microsoft.Build.Tasks.CodeAnalysis.dll. Could not load file or assembly 'file:///C:\Users\Bryan\Source\Workspaces\TestProject\ContosoUniversity\packages\Microsoft.Net.Compilers.1.0.0\tools\Microsoft.Build.Tasks.CodeAnalysis.dll' or one of its dependencies. Could not find the file. Confirm that the declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask. ContosoUniversity
Has this something to do with that Azure don't support ASP.NET 4.6?
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Hi all.
I have a problem. really need some help.
I have a form contains 2 usercontrols name: usercontrol 1 and usercontrol 2. I use System.Timers.Timer.Elapsed to redraw usercontrol 1 and usercontrol 2 follow interval(interval of usercontrol 1 = 100ms. interval of usercontrol 2 = 1000ms). I measure time to draw usercontrol 1 and usercontrol 2 and I realize that time to draw usercontrol 1 is increase when usercontrol 2 has been drawing, when usercontrol 2 complete, time to draw usercontrol 1 is decrease. Is there anyway to solve it(time to draw usercontrol 1 is stable, it's not depend on the drawing usercontrol 2).
modified 14-Oct-15 23:20pm.
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Why are you using a timer to re-draw ? Is this a game ?
Normally, if there's custom drawing being done in a UserControl (or other container), this is done by using the 'Paint event.
Please tell us what your goal is here. Is there any dependency (like accessing the same Database) between the two UserControls ? Are both of the UserControls instances of the same UserControl Object, or do they both inherit from a common Class or Interface ?
«I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center» Kurt Vonnegut.
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I create a usercontrol name: panel1, use timer.Elapsed += OnTimerTick; OnTimerTick will call draw a function. I add 2 panel1 name: panel11 and panel12 into a form. usercontrol 1 draw into panel11, usercontrol 2 draw into panel12.
modified 15-Oct-15 4:33am.
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Hi, You still haven't answered the question about why you are using Timers to control painting/drawing, and what it is your painting/drawing. Please be specific.
«I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center» Kurt Vonnegut.
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I want to redraw usercontrol 1 and usercontrol 2 follow cycle(usercontrol 1 and usercontrol 2 always redraw follow Timer.Interval of each control), so I use Timer.Elapsed event to do that.
It draws line, text, ...
Sorry for bad English.
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Perhaps if you could show us a cut down version of the paint code for both controls.
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public void DrawControl(Graphics g)
{
int X = 599;
int Y = 10;
int Width = 225;
using (GraphicsPath path = GraphicsHelper.Create(X, Y, 224, 119, 5))
{
using (Pen frameWithBlackBgrd = new Pen(CWColors.FrameWithBlackBgrd))
{
g.DrawPath(frameWithBlackBgrd, path);
}
}
if (GuiResInfoMng.Instance.Lang != null && GuiResInfoMng.Instance.Param != null)
{
using (SolidBrush fixedTextWithBlackBgrd = new SolidBrush(CWColors.FixedTextWithBlackBgrd))
{
g.DrawString(GuiResInfoMng.Instance.Lang.GetStr(LangId.IDS_COM_TOTALCNT),
FontFactory.Instance.GetFont(LangId.FNT_M2), fixedTextWithBlackBgrd, X, Y);
g.DrawString(GuiResInfoMng.Instance.Lang.GetStr(LangId.IDS_COM_PASS), FontFactory.Instance.GetFont(LangId.FNT_M2),
fixedTextWithBlackBgrd, X, Y + 23);
g.DrawString(GuiResInfoMng.Instance.Lang.GetStr(LangId.IDS_COM_NG), FontFactory.Instance.GetFont(LangId.FNT_M2),
fixedTextWithBlackBgrd, X - 1, Y + 46);
}
}
using (SolidBrush variableText = new SolidBrush(CWColors.VariableText))
{
g.DrawString(ParamHelper.GetParamStr(ParamId.TOTALCOUNT).Trim(), FontFactory.Instance.GetFont(LangId.FNT_M2), variableText, X + Width - 60, Y);
g.DrawString(ParamHelper.GetParamStr(ParamId.PASSCOUNT).Trim(), FontFactory.Instance.GetFont(LangId.FNT_M2), variableText, X + Width - 60, Y + 23);
g.DrawString(ParamHelper.GetParamStr(ParamId.NGCOUNT).Trim(), FontFactory.Instance.GetFont(LangId.FNT_M2), variableText, X + Width - 60, Y + 46);
}
}
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That's the paint routine for one control, not two.
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usercontrol 2 will invoke draw function:
public void DrawGraph(Graphics g)
{
g.SmoothingMode = SmoothingMode.HighSpeed;
_frameXBar.DrawBackground(g, XbarPos);
_frameNumber.DrawBackground(g, NumberPos);
_frameRS.DrawBackground(g, RsPos);
DrawXBarBase(g);
DrawXbarGraph(g);
DrawRSBase(g);
DrawRSGraph(g);
DrawNumber(g);
}
DrawGraph function will call some function:
Ex:
private void DrawRSGraph(Graphics g)
{
if (IsAllLine)
{
if (IsR)
{
if (IsFullLine)
{
DrawPolyline(_dataAllLineRFullNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
else
{
DrawPolyline(_dataAllLineRPassNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
}
else
{
if (IsFullLine)
{
DrawPolyline(_dataAllLineSFullNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
else
{
DrawPolyline(_dataAllLineSPassNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
}
}
else
{
if (IsR)
{
if (IsFullLine)
{
DrawPolyline(_dataForLineRFullNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
else
{
DrawPolyline(_dataForLineRPassNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
}
else
{
if (IsFullLine)
{
DrawPolyline(_dataForLineSFullNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
else
{
DrawPolyline(_dataForLineSPassNumber, g, _frameRS.Width, _frameRS.Height, CalculateHeightRS, RsPos);
}
}
}
}
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Hi, I'd like to suggest you now go back to your original question here and edit it so it includes the information/code you've shared.
cheers, Bill
«I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center» Kurt Vonnegut.
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How many "cores" does your CPU have? Getting the most out of multi-threading (usually) requires multiple cores.
You want control 1 to be "stable" ... What about control 2?
If control 1 can be stable at the expense of control 2, then you could implement a "priority" system where control 1 is allowed to preempt control 2 (for drawing), but control 2 is not allowed to preempt control 1. There are various ways of blocking and testing for locks to accomplish this.
Be aware that "drawing" has always been a fairly slow operation relative to compute time (that's why it is not wise to update a "progress bar" too frequently when it comes to critical operations).
Also, 100ms is (usually) the limit at which a user can detect "lag" in a UI; you might consider raising the interval for control 1 to 200ms and checking the results.
And, since the interval of control 2 is a multiple of control 1, you might consider using a single timer, and "dispatching" control 2 once for every n times control 1 is dispatched; i.e. dispatch either control 1 or 2, but not so that both are running at the same time (when redrawing).
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Thank for your reply.
My cpu has 2 core.
The first I want control 1 to be stable, control 2 still not care.
I measure time to draw control 1, AVG value = 15ms-> 20 ms, usually it ~ 10 ms, however when control 2 has been drawing, time to draw control 1 increase up to ~ 200ms. When control 2 complete it decrease down to ~ 10ms.(I want to both control are running at the same time, the drawing of controls is independence)
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Your measurements seem to indicate that the controls cannot run at the same time if you expect control 1 to always draw at under 100ms without considering what control 2 is doing (or vice versa).
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I can confirm that both control are draw at the same time.
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I have a 20 records in a database table and I want to read a field in each record fieldA. For each record that fieldA contains data I want to do a count of that field. So if 10 records have data in fieldA then my count for fieldA will be 10.
Anyone know how to do this in C# ?
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You can probably use some clever SQL to do it; try the database forum.
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Well, assuming you are connecting to a database and want to use straightforward SQL, you could just execute the following scalar command:
SELECT COUNT(1) FROM MyTable WHERE FieldA IS NOT NULL So, you would have something like
private int GetCommand(IDbConnection dbConnection)
{
IDbCommand command = dbConnection.CreateCommand();
command.CommandText = "SELECT COUNT(1) FROM MyTable WHERE FieldA IS NOT NULL";
command.CommandType = CommandType.Text;
dbConnection.Open();
object output = command.ExecuteScalar();
dbConnection.Close();
int retValue;
int.TryParse(output, ref retValue);
return retValue;
}
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