Re: ComboBox - Set first display item in dropdown list - C# Discussion Boards

hi
How about using int32.parse(textbox.text) ?

Banshi Khinchi

You see the following code :

private void button1_Click(object sender, System.EventArgs e)
{
int number = 0;
try
{
number = System.Convert.ToInt32(textBox1.Text);
}
catch(Exception ex)
{
System.Windows.Forms.MessageBox.Show("Input is not a number !");
textBox1.Focus();
return;
}
DoSomething(number);
}

private void DoSomething(int iNumber)
{
// Your code is here ...
}

with textBox1, textBox2 are two instances of TextBox class and button1 is a instance of Button class.

NPS.

Handle the Validating event for both text boxes:

private void TextBox_Validating(object sender, CancelEventArgs e)
{
    TextBox textBox = sender as TextBox;
    if(textBox == null)  // Ensure this is indeed a TextBox
        return;
 
    // Allow the user to leave the text box without typing anything
    if(textBox.TextLength == 0)
        return;
 
    bool error = false;
 
    try
    {
        int n = Convert.ToInt32(textBox);
        if(n < 0 || n > 100)  // Check range if necessary
            error = true;
    }
    catch(FormatException)
    {
        // Could not parse the number
        error = true;
    }
    finally
    {
        if(error)
        {
            MessageBox.Show("Please enter a valid number");
 
            textBox.SelectAll();
            textBox.Focus();
 
            e.Cancel = true;  // Don't allow focus to leave the control
        }
    }
}

When the user tries to take focus away from the control, its contents will be validated. If invalid, the user won't be allowed to leave the control unless he corrects it or leaves it empty.

Then in you button handler, just validate that the text boxes have anything. If they do, it's surely a valid number.

I hope this helps!

-- LuisR

Luis Alonso Ramos
Intelectix - Chihuahua, Mexico

Not much here: My CP Blog!

The amount of sleep the average person needs is five more minutes. -- Vikram A Punathambekar, Aug. 11, 2005

In keypress of textbox-es write this code:

e.Handled = e.KeyChar < '0' || e.KeyChar > '9';

u are able to write only numers no other charachters

I hope this helps u

I have a value in the ComboBox that does not appear in its drop down list. When I drop down the list, I want the nearest match to be selected without changing the current value.

So far I have a custom control that I inherited from System.Windows.Forms.ComboBox, and I have the following code attempting to do this.

protected override void OnDropDown(EventArgs e)
{
string strValue = this.Text;
int nValue = Convert.ToInt32(strValue);

for (int i = 0; i < this.Items.Count; i++)
{
int nItem = Convert.ToInt32(this.Items[i].ToString());
if (nValue >= nItem && nValue < nItem + 50)
{
this.SelectedIndex = i;
break;
}
}

base.OnDropDown(e);

this.Text = strValue;
}

If I remove "this.Text = strValue;", the nearest value is selected however the Text property will now contain this new selected value. I want to select the nearest value when the list drops down (for display purposes), but at the same time retain the value in the Text property.

--IAN

Hope this helps...........

private string buffer = String.Empty;
private Timer timer = null;
const int MAX_BUFFERSIZE = 1024;

this.timer = new Timer();
this.timer.Interval=1000;
this.timer.Tick+=new EventHandler(this.TimerTick);
this.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.OnKeyPress);

public void TimerTick(object sender,EventArgs eArgs)
{
this.buffer = String.Empty;
this.timer.Stop();
}

protected void OnKeyPress(object sender, KeyPressEventArgs e)
{
try
{
e.Handled = true;

if ( this.buffer.Length == 0 )
{
timer.Start();
}

if ( buffer.Length < MAX_BUFFERSIZE )
{
buffer += e.KeyChar.ToString();
Console.WriteLine(buffer);
}

int startIndex = 0;

if ( this.SelectedIndex != -1 )
{
startIndex = this.SelectedIndex;
}
bool found = false;
for ( int index = startIndex; index <= this.Items.Count - 1; index++)
{
string text = String.Empty;
if ( this.DisplayMember != String.Empty )
{
PropertyInfo propertyInfo = base.Items[index].GetType().GetProperty(base.DisplayMember);
text = propertyInfo.GetValue(base.Items[index], null).ToString();
}
else
{
text = base.Items[index].ToString();
}

if ( text.Length > this.buffer.Length )
{
if ( text.ToUpper().StartsWith(buffer.ToUpper()))
{
found = true;
this.SelectedIndex = index;
break;
}
}
}
if ( !found )
{
for ( int index = 0 ; index < startIndex; index++)
{
string text = String.Empty;
if ( this.DisplayMember != String.Empty )
{
PropertyInfo propertyInfo = base.Items[index].GetType().GetProperty(base.DisplayMember);
text = propertyInfo.GetValue(base.Items[index], null).ToString();
}
else
{
text = base.Items[index].ToString();
}

if ( text.Length > this.buffer.Length )
{
if ( text.ToUpper().StartsWith(buffer.ToUpper()))
{
this.SelectedIndex = index;
break;
}
}
}
}
}
catch ( Exception ex )
{
Console.WriteLine(ex.Message);
}
}

Unfortunately I'm not looking for autocomplete type of functionality.

Let's say that combo box list contains times of the day in half hour increments (12:00 am, 12:30 am, 1:00 am, ...). This allows for easy selection of a time. However the user needs to be allowed to enter a time that does not appear in the list, say 1:09 am (and actually by default will be loaded with the current time). This is all easy to do, and does not require any extraordinary coding.

Now for the tricky part. Let's say the combo box has a value of, say 3:12 pm. When the user clicks to drop down the list, the value 3:12 pm will not be found in the list, so it will be positioned with 12:00 am as the first item in the drop down list. Just as a nice to have, I'd like to see the list "auto-scroll" to the nearest value contained in the list when the list is dropped down. In this case it would be 3:00 pm. In addition, at the same time as we are "auto-scrolling", we need to retain the original value of 3:12 pm in the combo box. I know, quite a challenge.

Microsoft currently has this type of functionality in Outlook when setting up a new appointment on the Calendar. If they can do, should we be able to do it?

--Ian

I have a solution to my post, and here it is.

<br />
public class TimePicker : ComboBox<br />
{<br />
	bool m_fIsDropDown = false;<br />
	string m_strTime = string.Empty;<br />
	int m_nSelectedIndex = -1;<br />
	<br />
<br />
	public TimePicker() : base()<br />
	{<br />
	}<br />
<br />
	private void LoadTimes()<br />
	{<br />
		if (this.Items.Count < 1)<br />
		{<br />
			DateTime t = new DateTime(2005, 10, 11, 0, 0, 0, 0);<br />
			while (t < new DateTime(2005, 10, 12))<br />
			{<br />
				this.Items.Add(t.ToShortTimeString());<br />
				t = t.AddMinutes(30);<br />
			}<br />
		}<br />
	}<br />
<br />
	protected override void OnCreateControl()<br />
	{<br />
		base.OnCreateControl();<br />
<br />
		LoadTimes();<br />
	}<br />
<br />
	protected override void OnDropDown(EventArgs e)<br />
	{<br />
		base.OnDropDown(e);<br />
<br />
		m_strTime = this.Text;<br />
		DateTime dtmValue = DateTime.Now;<br />
		try <br />
		{<br />
			dtmValue = Convert.ToDateTime(m_strTime);<br />
		}<br />
		catch <br />
		{<br />
			return;<br />
		}<br />
<br />
		for (int i = 0; i < this.Items.Count; i++)<br />
		{<br />
			DateTime dtmItem = Convert.ToDateTime(this.Items[i].ToString());<br />
			if (dtmValue >= dtmItem && dtmValue < dtmItem.AddMinutes(30))<br />
			{<br />
				this.SelectedIndex = i;<br />
				m_nSelectedIndex = i;<br />
				break;<br />
			}<br />
		}<br />
<br />
		m_fIsDropDown = true;<br />
	}<br />
<br />
	protected override void OnMouseDown(MouseEventArgs e)<br />
	{<br />
		if (m_fIsDropDown == true)<br />
		{<br />
			this.SelectedIndex = m_nSelectedIndex;<br />
			this.Text = m_strTime;<br />
		}<br />
		else<br />
		{<br />
			base.OnMouseDown(e);<br />
		}<br />
	}<br />
<br />
	protected override void OnMouseUp(MouseEventArgs e)<br />
	{<br />
		if (m_fIsDropDown == true)<br />
		{<br />
			this.SelectedIndex = m_nSelectedIndex;<br />
			this.Text = m_strTime;<br />
			m_fIsDropDown = false;<br />
		}<br />
		else<br />
		{<br />
			base.OnMouseUp(e);<br />
		}		<br />
	}<br />
}	<br />

--IAN

is there a way to hide a process from System.Diagnostics.GetProcesses()? so it would not list it? or if its listed not be able to access its information?

also is there a way to tell which process is attempting to hook to yours? or is attempting to access yours?

so if i say:

Within Process "B"
{
System.Diagnostics.Process tProcess = System.Diagnostics.GetProcessByName("B");

event(System.Diagnostics.Process pAnotherProcess)// when another process is accessing yours
{
if(pAnotherProcess.ProcessName == "B")
Message("your accessing your own process");
}
}

i know this might be C++ section but just want to find out what i need to do to detect this?

or away to catch any calles to get process information.

CALLER-->GetProcess()-->RedirectToMyFunction-->Pass/Reject Request-->CALLER
Smile | :)

-- modified at 11:13 Thursday 13th October, 2005

mishen` wrote:
is there a way to hide a process from System.Diagnostics.GetProcesses()? so it would not list it?

No.

mishen` wrote:
or if its listed not be able to access its information?

Process Security and Access Rights[^]. You'll have to P/Invoke a bunch of functions and structures to alter your process' ACL. There is nothing in the .NET BCL (1.0 and 1.1) that supports this.

mishen` wrote:
also is there a way to tell which process is attempting to hook to yours?

No.

mishen` wrote:
or is attempting to access yours?

No.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

thanks for being streight forward.

so most questions answered thanks. most glad that the process cant tell if your hooking to it.

thanks for he link.:->

Smile | :)

Hi all,

i have a rich textbox and i want that the richtextbox

should be of A4 size i.e. it should accommodate contents
that of A4 size

the user should not be able to enter text if the contents

have reached the A4 limits

Please if anyone of you could help me

Thanks

Pramod

Hi!

I want my application to close if the user is not performing any keyboard or mouse activity and no process (copying file, query database etc.) is running for 5 minutes.

Can somebody how can I do this?

Thank You

This article my give you a hint:

http://www.codeproject.com/csharp/uim.asp[^]

Good luck!

-- LuisR

Luis Alonso Ramos
Intelectix - Chihuahua, Mexico

Not much here: My CP Blog!

The amount of sleep the average person needs is five more minutes. -- Vikram A Punathambekar, Aug. 11, 2005

I think it works for Keyboard and Mouse activities only but what about the running processes in my application i.e. read/write files or any non-idle process.

I want my application to trigger on external application start/close events but haven't been able to figure out how to do this.

For example. I would like my application to execute a certain task every time Internet Explorer is executed on the system.

I would greatly appreciate if someone had a solution to this!

Thanks!

// T

Well, one way you could do this (which isn't the best way I don't imagine, but I can't think of any other way at the moment) is to create a task watcher process that watches the task list and kicks off event "alerts" that you set when certain tasks are created/exited.

Yes, this is how I do it now..
I don't feel that this is the correct way of doing it though. I would imagine that you could hook on IE or trap a windows message to do this instead. I've tried searching for it on the net and haven't found anything Frown | :-(

Hopesfully someone will have a solution Smile | :)

Problem!
I want to show some icons against menu items just like when we open Msword in its File menu there is different icon to the left most of each menu item . How to achieve this any help or idea.
Thanks In Advance

Visual Studio .NET 2005 (beta) provides MenuStrip control for this.
You need to handle the DrawItem event of the menu and set ownerdraw property to true (sorry I don't know the details. google for owner drawn menu with bitmap)
If you don't come up with the solution then google for VolveNet Menu Extender

Hello!

I am sorry if I am unable to state my problem clearly.

I am using an SQL Server 2000 database for my .NET Windows application(VB/C#).
My main MDI form has a large number of menus and options.

Do I use a table in the database for maintaining the users and their encrypted password and other details?
i.e User ID, Full Name, Password, Working Shift, Email Address etc.
OR
I must use SQL Server logins and roles?

If I use the first approach my triggers and stored procedures will not be able to utilize the User_Name() SQL Server function for logging the User transactions.
If I use the second approach, then, where do I store the detailed information about the user (i.e infomation about the user as in Windows Active Directory for a domain)

In most of the forms in my application each form is related to a single table of the database. And each of those forms performs Update, Insert, Delete operations on the table.
How do I enable/disable the Insert, Update, Delete buttons on my form accoring to the user permissions on that table?

Does SQL Server's Application Role have something to do with my problem?
And
How do I use the Application Role best.

I hope you understand my problem.

Anticipating a quick reply.
Thank you.

-- modified at 8:23 Thursday 13th October, 2005

You can do whatever suits your application best, but it's typical in large application settings with lots of users to have all access to the database take place through a small number (or one) login. Doing so has certain administrative benefits as well as performance benefits to the database server (wrt connection pooling, and cacheing commands).

If you're interested in doing declarative security, I would recommend checking out the IPrincipal interface and the classes that inherit from it. If you're writing a WinForms application, you may be able to take advantage of the WindowsPrincipal to leverage your AD security without making a lot of concessions. If that's not an option, you can make your own Principal, and roll your own authentication scheme as well. Either way, the Principal is a built-in authorization structure in .Net.

Best of luck.

The most exciting phrase to hear in science, the one that heralds the most discoveries, is not 'Eureka!' ('I found it!') but 'That's funny...’

Hello,

How can I create a standalone .EXE file for my Windows Application, and the installation files for this application?

Thank you.

Not easily. The only langauge in vs.net that will produce native code directly is unmanaged(normal) c++. There are a few 3rd party tools that will compile the IL produced by the other .net langauges into an executable but they're all afaik expensive.

It is theoretically possible but what possible application would there be for doing such a thing? Not only would your application have to be "compiled" again but all subsequent assemblies have to be sucked in. You'd either end up with a very large executible or a complete duplication of the .Net Framework in a C runtime format.

You could ask the same thing about VB 6 to C and note no one does this. The possible advantages of changing runtime formats is way outweighed by the complexity of doing so.