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Do not allow Enter Key to make a new line in MultiLine TextBox C#

I set the property Multiline=true;.
I do not want to allow the Enter Key to make a new line.
How can I solve this issue?

That could be as simple as listening to TextChanged event and then executing the following line inside it:
txtYourTextBox.Text = txtYourTextBox.Text.Replace(Environment.NewLine, "");
This solution involves some screen flicker though. A better way is to prevent it entirely by listening to KeyDown event:
private void txtYourTextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
e.SuppressKeyPress=true;
}

Well, I am quite late to the party, but for others who read this I would mention that there is a property named TextBox.AcceptsReturn (Boolean).
Just set it in the properties window of the TextBox.
I had the same problem just the other way round: I had a multiline TextBox, but it didn't allow me to enter Returns.
Further information here:
https://learn.microsoft.com/dotnet/api/system.windows.forms.textbox.acceptsreturn?view=net-5.0

SendKeys {SUBTRACT} not working

I've searched the Internet and this web site for any clues to fix my issue, but haven't found one.
I have a method that expects a string and then does SendKeys.SendWait(str). Everything works like passing in "{ENTER}" or just typing normal text.
But! If I pass in "{SUBTRACT}" it just doesn't work. I've also tried passing in the ASCII presentation of the key, but it threw exception that its unsupported.
I've also tried just doing SendKeys.Send("{SUBTRACT}") - no results what so ever.
Its just not doing anything. However, when I press the minus button on the keypad or on the top of the keyboard - functionality works.
Please note that this is using windows Automation Framework. May be this is what causing the problem. Has anyone had the same issues?

I have tried to show messagebox on Subtract KeyDown event. I have sent Subtract key on my button click event. But, make sure you have enabled KeyPreview property of your windows form.
private void button1_Click(object sender, EventArgs e)
{
SendKeys.Send("{SUBTRACT}");
}
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Subtract)
this.UltraGrid1.Rows.CollapseAll(true);
}

Control is not getting focused on Keyup event

Hi all I have created a dynamic combo box with a Textbox and a button to appear as dropdown style, every thing works fine but I handled keyup event for the textbox so that when user enter some text I will search for the results and display them
private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
//Some code to filter my data
textBox1.Focus();
}
But I am unable to set the focus Immediately back to the textbox after results getting displayed so can some one help me
Code I used is from here
http://www.planetsourcecode.com/vb/scripts/showcode.asp?txtCodeId=8554&lngWid=10

I have found that the Focus() method is a bit flaky.
Other options:
textBox1.Select(textBox1.Text.Length - button1, 1);
...or simply:
textBox1.Select();
If you can verify that something else is going wrong, then this might be off base, otherwise you might simply be fighting weirdness.

C# and backspace detection in textbox in order to reload listbox

As part of this assignment for my class, in which I have a listbox which is connected to a database and it displays the first and last name of the students. I have also created a search feature in which the user types in the first and/or last name they are looking for in a textbox and when they press the "search" button it displays the filtered results appear in the listbox.
The last part of the question asks me to detect when the user clears the textbox, to once again display the original data in the listbox. I have the data in a method called databaseload()and so it is really down to how to I get my program to detect that the listbox is once again empty.
I found a couple of things online, and when I tried them, it didn't work.
private void searchTextBox_KeyPress(object sender, KeyPressEventArgs e){
if (e.KeyChar == 8)
{
databaseload();
}
}
and I have also tried KeyDown
I also don't want it to reload when first backspace is detected. I want it to reload the listbox when the searchTextBox has nothing in it.
Your help is greatly appreciated.

You should handle the KeyUp event, which fires after the key has been entered into the text.

There is a TextChanged event which seems more appropriate than manually detecting backspaces. The delete key can remove all the text as well, or someone might just highlight all of the text and cut it to the Clipboard.
Example of using the TextChanged event:
private void textBox_TextChanged(object sender, EventArgs e)
{
if (string.IsNullOrEmpty(((TextBox)sender).Text))
{
// reload database
}
}

Should the TextBox raise the validating event when Return is clicked?

I'm a bit confused, as far as I remember the Textbox used to launch the Validating event when the used pushed the Enter key after entering the desired text but this is not happening now.
Do you know if this is the expected behavior or not?
Thanks.

see:Control.Validating Event
Note: If the CausesValidation property is set to false, the Validating and Validated events are suppressed.

I use a method similar to Javed Akram's answer, but instead of calling the Validating function, I just call focus on the parent...
private void TextBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Enter)
{
(sender as TextBox).Parent.Focus();
}
}
When the TextBox itself looses focus it will call its own Validating event

No not as far as I remember. The TextBox generally only validates when focus is gotten/lost unless something triggers it manually.
Hvae a look at Bolu's link for a list of validating triggers

Validating event is fired when the control lost its focus, so you can fire validating event yourself in keyPress event after checking, if the entered key is Enter key.
Sample Code:
private void someTextBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Enter)
{
someTextBox_Validating(sender, new CancelEventArgs());
}
}