Validate a textbox in a windows form

Question

Windows form application(.Net 3.5) I have a textbox and a button on the form. I want to disable the button once the textbox is empty. I don't want to use this method. Because the button is still enabled.

Thanks.

score 3 · Accepted Answer · answered Jun 27 '12 at 18:13

3

In the event handler for TextChanged, simply determine if the text box contains any data. If it does, enable it. Otherwise, disable it. Add your event handler and then implement something like the following,

private void textBox1_TextChanged(object sender, EventArgs e)
{
   button1.Enabled = !(textBox1.Text == String.Empty);
}

answered Jun 27 '12 at 18:13

George Johnston

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Or: `button1.Enabled = textBox1.Text.Length>0`. – Uwe Keim Jun 27 '12 at 18:16

score 0 · Answer 2 · answered Jun 27 '12 at 18:14

0

Handle the on text change event

check and see what textbox.text is like this

  if(string.IsNullOrEmpty(textbox1.text))
 {
  Button1.enabled = false;
 }

answered Jun 27 '12 at 18:14

Micah Armantrout

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TextBox *Text* property values will never be null. – George Johnston Jun 27 '12 at 18:16
Actually thats not true ... http://stackoverflow.com/questions/4780819/c-sharp-winform-how-textbox-became-null-on-button-click-second-time – Micah Armantrout Jun 27 '12 at 18:16
Actually it is. Try setting a TextBox Text value to null and then inspecting the Text property. It will be an empty string. – George Johnston Jun 27 '12 at 18:23

score 0 · Answer 3 · answered Jun 27 '12 at 18:14

0

if you want to disable the textbox, then using textChanged:

if (textbox.Text == ""){
   button.Enabled = false;
}

Hope it helps

answered Jun 27 '12 at 18:14

Ignacio Gómez

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score 0 · Answer 4 · answered May 18 '15 at 13:38

Make button1.Enabled = false;

and add EventHandler to textbox1.TextChanged = new System.EventHandler(SearchBoxTextChanged);

private void textbox1_TextChanged(object sender, EventArgs e)
    {
        button1.Enabled = (textBox1.Text.Trim() != string.Empty);
    }

Validate a textbox in a windows form

4 Answers4