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Zlobaton
Zlobaton

Reputation: 674

Check if Keys is Letter/Digit/Special Symbol

I override ProcessCmdKey and when I get Keys argument, I want to check if this Keys is Letter or Digit or Special Symbol.

I have this snippet

    protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    {
            char key = (char)keyData;
            if(char.IsLetterOrDigit(key)
            {
                Console.WriteLine(key);
            }
            return base.ProcessCmdKey(ref msg, keyData);
    }

Everything works for letters and digits. but when I press F1-F12 it converts them to letters.

Maybe someone knows better way to solve this task?

Upvotes: 8

Views: 49511

Answers (6)

RobHurd
RobHurd

Reputation: 2061

I have tried the following code but for some reason char.IsLetter() method is recognising the following keys as Letters???

F1, F8, F9, F11, F12, RightShift, LeftShift, RightAlt, RightCtrl, LeftCtrl, LeftWin, RightWin, NumLock.

This method doesn't seem to be that full proof regarding what it thinks is a letter.

if(char.IsLetter((char)e.Key) || char.IsDigit((char)e.Key))

Upvotes: 0

bernhof
bernhof

Reputation: 6320

Override the form's OnKeyPress method instead. The KeyPressEventArgs provides a KeyChar property which allows you to utilize the static methods on char.

As mentioned by Cody Gray in the comments, this method only fires on key strokes that have character information. Other key strokes such as F1-F12 should be processed in OnKeyDown or OnKeyUp, depending on your situation.

From MSDN:

Key events occur in the following order:

The KeyPress event is not raised by noncharacter keys; however, the noncharacter keys do raise the KeyDown and KeyUp events.

Example

protected override void OnKeyPress(KeyPressEventArgs e)
{
  base.OnKeyPress(e);
  if (char.IsLetter(e.KeyChar))
  {
    // char is letter
  }
  else if (char.IsDigit(e.KeyChar))
  {
    // char is digit
  }
  else
  {
    // char is neither letter or digit.
    // there are more methods you can use to determine the
    // type of char, e.g. char.IsSymbol
  }
}

Upvotes: 14

Charles Lambert
Charles Lambert

Reputation: 5132

you need either a giant switch/case statement or check for ranges. You may find it easier to check for the keys you want to exclude, depending on which there is fewer of. Look at this for all the possible values. http://msdn.microsoft.com/en-us/library/system.windows.forms.keys.aspx

if (keyData >= Keys.A && keyData <= Keys.Z)
   // do something

or

switch(keyData) {
case Keys.Add:
case Keys.Multiply:
// etc.
   // do something
   break;
}

Upvotes: 0

Bala R
Bala R

Reputation: 108967

Try

if( !(keyData >= Keys.F1 && keyData <= Keys.F12))
{
    char key = (char)keyData;
    if(char.IsLetterOrDigit(key))
    {
        Console.WriteLine(key);
        return false;
    }

}
return base.ProcessCmdKey(ref msg, keyData);

Upvotes: 2

Cheng Chen
Cheng Chen

Reputation: 43523

if (keyData >= Keys.F1 && keyData <= Keys.F12)
{
     //one of the key between F1~F12 is pressed
}

Upvotes: 0

Brad Christie
Brad Christie

Reputation: 101614

Try using keyData.KeyCode and maybe even testing within a range instead of using the Char.IsLetterOrDigit. e.g.

if (keyData.KeyCode >= Keys.D0 && keyData.KeyCode <= Keys.Z) {
  ...
}

Upvotes: 1

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