How can I validate user entered string in textbox?

Now TextBox in Windows application of C# have something called as events
all u have to do is use the KeyPress event of the textbox and paste in the following code...

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            //only numbers code

            if (char.IsNumber(e.KeyChar) == false)
            {
                e.Handled = true;
            }
            //backspace workin keycode
            if (e.KeyChar == (char)Keys.Back)
            {
                e.Handled = false;
            }
            //if u want that alphabets must be entered then just use
           // char.IsLower in place of char.IsNumber
        }

and ur done...

Do rate my answer once u find it useful

Thanks & Regards
Radix :rose:

for this kind of issue i have created a one article

just check below link you will get answer to your question
Enhanced Textbox Control

HI,

you use the Following code on windows application.
Only accept Numbers.

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{ //only numbers code
if (char.IsNumber(e.KeyChar) == false) {
e.Handled = true;
}
//backspace workin keycode
if (e.KeyChar == (char)Keys.Back)
{
e.Handled = false;
}
//if u want that alphabets must be entered then just use
// char.IsLower in place of char.IsNumber
}