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C# Compare the Key Pressed on the Keyboard

I have a textbox and a button.I'm saving the value(keyboard key) entered in the TextBox.I need to give a message when I press the right keyboard key.
private void btn_Click(object sender, EventArgs e)
{
Properties.Settings.Default.text1 = text1.Text;
Properties.Settings.Default.Save();
}
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyData == text1.Text) //--------->> error
{
MessageBox.Show("success");
}
}
how can I provide this condition?

maybe easier it will be to use KeysConverter
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
KeysConverter convertor = new KeysConverter();
string keyPressed = convertor.ConvertToString(e.KeyValue);
if (keyPressed == text1.Text)
{
//do stuff
}
}

If you compare with one char text. You can try this.
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (txt.Text.Length == 1 && e.KeyValue == (int)txt.Text[0]) //--------->> error
{
MessageBox.Show("success");
}
}

Enter key in C#

I have a code like below
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
{
if (!textBox1.AcceptsReturn)
{
button1.PerformClick();
}
}
}
After I hit Enter, it'll send a message to another textbox and begin a new line. Can anyone help me to bring the cursor back to its first line?
I tried textBox1.SelectionStart, SelectionLength and Focus but it doesn't work, is there any another way?

You can prevent that the keypress is passed on to the control by setting the KeyPressEventArgs.Handled property to true:
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
{
if (!textBox1.AcceptsReturn)
{
button1.PerformClick();
e.Handled = true;
}
}
}
As you mentioned in a comment that you are implementing a chat app, you also might want to implement the typical behavior of Shift+Return inserting a new line:
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyValue == 13 && !e.Shift)
{
if (!textBox1.AcceptsReturn && !string.IsNullOrEmpty(textBox1.Text))
{
button1.PerformClick();
textBox1.Text = "";
e.Handled = true;
}
}
}

To set cursor position to the beginning of a textbox, use the following...
I will hazard a guess that you didn't use these in combination with each other...
textBox1.SelectionStart = 0;
textBox1.SelectionLength = 0;

Multiple TextChanged and KeyPress event

I have a lot of TextBox controls. For every TextBox control I get their text_Changed and key_Press events. Because of this my Form.cs becomes too crowded. My question is this, is it possible to make this more space free? Some events only consist of one function.
Sample Code:
private void txtItem_TextChanged(object sender, EventArgs e)
{
showButtonSave();
}
private void txtItem_KeyPress(object sender, KeyPressEventArgs e)
{
showButtonSave();
char ch = e.KeyChar;
if (ch == (char)Keys.Enter)
e.Handled = true;
}
private void txtItem2_TextChanged(object sender, EventArgs e)
{
showButtonSave();
}
private void txtItem2_KeyPress(object sender, KeyPressEventArgs e)
{
showButtonSave();
char ch = e.KeyChar;
if (ch == (char)Keys.Enter)
e.Handled = true;
}

On your txtItem2 you can go to its properties and there where it says ontextchange you should see it is set to txtItem2_KeyPress change that to txtItem_KeyPress then they will both use
private void txtItem_KeyPress(object sender, KeyPressEventArgs e)
{
showButtonSave();
char ch = e.KeyChar;
if (ch == (char)Keys.Enter)
e.Handled = true;
}

You can create one event for each type(txtItem_TextChanged / txtItem_KeyPress)and map it to all TextBox. With the help of sender you can get the actual control and manipulate as you want.

How to stop the first character in a text box from being '.'?

This is the code I currently have:
private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar) && e.KeyChar != '.';
if (e.KeyChar == '.' && (sender as TextBox).Text.IndexOf('.') > -1) e.Handled = true;
}

KeyPress isn't good enough to do this kind of validation. A simple way to bypass it is to paste text into the text box with Ctrl+V. Or the context menu, no key event at all.
In this specific case, the TextChanged event will get the job done:
private void textBox_TextChanged(object sender, EventArgs e) {
var box = (TextBox)sender;
if (box.Text.StartsWith(".")) box.Text = "";
}
But there's a lot more to validating numeric values. You also need to reject stuff like 1.1.1 or 1.-2 etcetera. Use the Validating event instead. Drop an ErrorProvider on the form and implement the event like this:
private void textBox_Validating(object sender, CancelEventArgs e) {
var box = (TextBox)sender;
decimal value;
if (decimal.TryParse(box.Text, out value)) errorProvider1.SetError(box, "");
else {
e.Cancel = true;
box.SelectAll();
errorProvider1.SetError(box, "Invalid number");
}
}

You probably want to use the TextChanged event, since the user could paste in values. For the best experience given the requirements, I'd suggest simply removing any leading . characters.
void textBox1_TextChanged(object sender, EventArgs e)
{
if (textBox1.Text.StartsWith("."))
{
textBox1.Text = new string(textBox1.Text.SkipWhile(c => c == '.').ToArray());
}
}
This does not address a requirement to use only digits -- wasn't clear in the question if that is the case.

This works for copy and pasting too.
private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
int decimalCount=0;
string rebuildText="";
for(int i=0; i<textBox1.Text.Length; i++)
{
if (textBox1.Text[i] == '.')
{
if (i == 0) break;
if (decimalCount == 0)
rebuildText += textBox1.Text[i];
decimalCount++;
}
else if ("0123456789".Contains(textBox1.Text[i]))
rebuildText += textBox1.Text[i];
}
textBox1.Text = rebuildText;
textBox1.SelectionStart = textBox1.Text.Length;
}

You can try this:
private void TextBox_TextChanged(object sender, EventArgs e)
{
TextBox.Text = TextBox.Text.TrimStart('.');
}

Disable warning/error beep when changing focus

Whenever I change the focus from one textbox to another it plays an irritating warning/error beep.
Example:
public void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Return)
textBox2.Focus();
}
whenever I press Enter it changes the focus to textBox2 and gives the warning beep.
Any help to disable this would be appreciated.
Thank you.

I think you want to add e.Handled = true to the event handler:
public void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Return)
{
textBox2.Focus();
e.Handled = true;
}
}
A side node: you should be able to use the KeyCode instead of the KeyChar property, avoiding the cast:
public void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyCode == Keys.Return)
{
textBox2.Focus();
e.Handled = true;
}
}

e.SuppressKeyPress = true;