Restricting Input to Numbers Only In Textbox? (c#) [closed]

Question

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.

Closed 9 years ago.

Please excuse me for asking this, I have looked at various different questions relating to this and I still can not get it to implement.

Using the answers I have looked at, I have gathered this, and applied this coding to my text box.

private void TxtBox5_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!(Char.IsDigit(e.KeyChar) || (e.KeyChar == (char)Keys.Back)))
            e.Handled = true;
    }

Now, when I proceed to run the program, I am still able to enter letters into it. I do not know what to do next, so any solution would be great. thanks.

Answer 1

Okay this is what i made just now, it works 100% just tested it.Note that my textBox is named serialTxtBox, you can change it to yours.

void serialTxtBox_TextChanged(object sender, EventArgs e)
        {
            bool enteredLetter = false;
            Queue<char> text = new Queue<char>();
            foreach (var ch in this.serialTxtBox.Text)
            {
                if (char.IsDigit(ch))
                {
                    text.Enqueue(ch);
                }
                else
                {
                    enteredLetter = true;
                }
            }

            if (enteredLetter)
            {
                StringBuilder sb = new StringBuilder();
                while (text.Count > 0)
                {
                    sb.Append(text.Dequeue());
                }                

                this.serialTxtBox.Text = sb.ToString();
                this.serialTxtBox.SelectionStart = this.serialTxtBox.Text.Length;
            }
        }

EDIT: Definitely you are doing something wrong. In your form constructor which is named like your form. In my case SerialGenerator, you need to initialize the event. In my case :

public SerialGenerator()
        {
            InitializeComponent();
            this.serialTxtBox.TextChanged += serialTxtBox_TextChanged;
        }

this will fire the method everytime someone enters something in your textBox. Make sure you rename it to your textbox's name

Answer 2

You can try this:

private void TxtBox5_KeyPress(object sender, KeyPressEventArgs e)
{
    if(!(Char.IsDigit(e.KeyChar) || Char.IsControl(e.KeyChar)))
        { e.Handled = true; }
}

I don't think this is the best one, but you may make this work by tweaking a little, I guess. I don't have VS right now to check what would work.

EDIT: My bad. I think you can use the above one not on keypress but on textchanged event of the textbox. It's more like a tweak than a solution. Just to make you progress if you are stuck and don't get a better solution.

Update: Updated the code. Please check if this one helps you.

Answer 3

Try this one,hope this works

   private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        int asciiCode = Convert.ToInt32(e.KeyChar);
        if ((asciiCode >= 48 && asciiCode <= 57))
        {


        }
        else
       {                MessageBox.Show("Not allowed!");
            e.Handled = true;


        }
    }

Answer 4

I have added events on code level, since there can be a possibility in your code not correctly event added to the control.

Note : The KeyPress event is not raised by noncharacter keys you need to use both KeyDown and KeyPress events

public partial class Form1 : Form
{
    private bool nonNumberEntered = false;
    public Form1()
    {
        InitializeComponent();
        textBox1.KeyDown+=new KeyEventHandler(textBox1_KeyDown);
        textBox1.KeyPress+=new KeyPressEventHandler(textBox1_KeyPress);
    }

    private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (nonNumberEntered == true)
        {
            e.Handled = true;
        }
    }

    private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        nonNumberEntered = false;

        if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
        {
            if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
            {
                if (e.KeyCode != Keys.Back)
                {
                    nonNumberEntered = true;
                }
            }
        }
        if (Control.ModifierKeys == Keys.Shift)
        {
            nonNumberEntered = true;
        }
    }
}

REF : Control.KeyPress Event

Answer 5

Try this ...

private void TxtBox5_KeyPress(object sender, KeyPressEventArgs e)
    {         
        int num = 0;
         e.Handled = !int.TryParse(e.KeyChar.ToString(), out num);

    }