How to mark TextBox as empty?

Question

When there is no text entered in any of TextBoxes, I want a new form to open with a message in it

if (rectangleBox.Checked == true && (int.Parse(side_a.Text) > 0 && 
    int.Parse(side_b.Text) > 0))
    {
      var drawRectangle = new Rectangles(70 + int.Parse(side_a.Text), 
      80 + int.Parse(side_b.Text),
      50 + int.Parse(side_a.Text), 70 + int.Parse(side_b.Text));
      Figures.Add(drawRectangle);
    };  

if (string.IsNullOrWhiteSpace(side_a.Text) &&
    string.IsNullOrWhiteSpace(side_b.Text) &&
    string.IsNullOrWhiteSpace(side_c.Text))
    {
        Form1 form1 = new Form1();
        Form1.ShowDialog();
    }

But I get an error on the following lines

    if (rectangleBox.Checked == true && (int.Parse(side_a.Text) > 0 && 
        int.Parse(side_b.Text) > 0))

"System.FormatException: 'Input string was not in a correct format.'"

Does this answer your question? [Check Whether a TextBox is empty or not](https://stackoverflow.com/questions/34298857/check-whether-a-textbox-is-empty-or-not) The exact duplicate — Pavel Anikhouski, May 26 '20 at 09:45
Folks are trying to help you but you make it really hard! What do you mean by 'mark' ??? Also: 'no text' or no valid numbers'? also data missing in one or all boxes? - General rule until you can't express your goal clearly you can't write code for it.. — TaW, May 26 '20 at 10:38

JeremyRock · Accepted Answer · 2020-05-26T09:42:09.720

4

You could use string.IsNullOrEmpty or string.IsNullOrWhiteSpace function to check if the TextBox is empty.

if(string.IsNullOrEmpty(TextBox1.Text))
{
  // do something
}

edited May 26 '20 at 09:42

answered May 26 '20 at 09:39

JeremyRock

396
1
8

1

Or IsNullOrWhiteSpace – JonasH May 26 '20 at 09:40
@JonasH You are correct. – JeremyRock May 26 '20 at 09:42
How does that answer the question? He asked not about testing but marking.. – TaW May 26 '20 at 10:13
@TAW Why the answer does not answer the question? What do you understand the question is? – JeremyRock May 26 '20 at 10:16
As I wrote above I do not understand the question. Maybe you guessed right, though.. – TaW May 26 '20 at 10:19
@JeremyRock Now I get an error when I try IsNullOrWhiteSpace or IsNullOrEmpty Add it above – DimityrU May 26 '20 at 10:26
Which error do you get?? – TaW May 26 '20 at 10:28
@ДимитърУзунов You are probably failing on int.Parse. Can you post the string values of side_a, side_b, side_c? – JeremyRock May 26 '20 at 10:29

How to mark TextBox as empty?

1 Answers1