Check if TextBox is empty and return MessageBox?

Question

I made this statement to check if TextBox is empty, but the MessageBox always shows up wether the TextBox is empty or not.

    private void NextButton_Click(object sender, EventArgs e)
    {
        decimal MarkPoints, x, y;
        x = HoursNumericUpDown.Value;
        y = MarkNumericUpDown.Value;
        MarkPoints = x * y;

        //decimal MarkPoints = (decimal)HoursNumericUpDown.Value * (decimal)HoursNumericUpDown.Value;


        DataGridViewRow dgvRow = new DataGridViewRow();
        DataGridViewTextBoxCell dgvCell =  new DataGridViewTextBoxCell();

        dgvCell = new DataGridViewTextBoxCell();
        dgvCell.Value = MaterialTextBox.Text;
        dgvRow.Cells.Add(dgvCell);

        dgvCell = new DataGridViewTextBoxCell();
        dgvCell.Value = HoursNumericUpDown.Value;
        dgvRow.Cells.Add(dgvCell);

        dgvCell = new DataGridViewTextBoxCell();
        dgvCell.Value = MarkNumericUpDown.Value;
        dgvRow.Cells.Add(dgvCell);

        dgvCell = new DataGridViewTextBoxCell();
        dgvCell.Value = MarkPoints;
        dgvRow.Cells.Add(dgvCell);

        dataGridView1.Rows.Add(dgvRow);

        MaterialTextBox.Clear();
        HoursNumericUpDown.Value = HoursNumericUpDown.Minimum;
        MarkNumericUpDown.Value = MarkNumericUpDown.Minimum;

        if (String.IsNullOrEmpty(MaterialTextBox.Text))
        {
            MessageBox.Show("Enter Material Name Please.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            //dataGridView1.Rows.Clear();
        }
        else
        {
            /*if (MarkNumericUpDown.Value < 50)
            {
                int index = dataGridView1.Rows.Add();
                dataGridView1.Rows[1].Cells[4].Value = "F";
            }
            else if (MarkNumericUpDown.Value > 50 && MarkNumericUpDown.Value <= 64)
            {
                dataGridView1.Rows[index].Cells[4].Value = "F";
            }*/

Please, fix the code sample. Pay attention to opening and closing braces — Dyppl
– Dyppl, Commented May 27, 2011 at 20:33

Dyppl · Accepted Answer · 2015-02-02 21:00:34Z

65

Try this condition instead:

if (string.IsNullOrWhiteSpace(MaterialTextBox.Text)) {
    // Message box
}

This will take care of some strings that only contain whitespace characters and you won't have to deal with string equality which can sometimes be tricky

edited Feb 2, 2015 at 21:00

answered May 27, 2011 at 18:49

Dyppl

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7 Comments

Dyppl Over a year ago

@ghost_j1: please, provide some context. Maybe extend your code sample to include the whole method

Dyppl Over a year ago

@ghost_j1: it's obviously not the whole code (it doesn't have the closing brace), but it's already obvious what the problem is, see my another answer. You clear the textbox before you validate it

sam Over a year ago

MOG... sooooooo stupid mistake made by me :S :S that's what happen when you programing all the day hehehe i need break

Dyppl Over a year ago

@ghost_j1: no problem, it happens. My advice is to break your code into smaller methods to make it easier to reason about.

Dyppl Over a year ago

@ghost_j1: also, feel free to accept an answer you found most useful if your problem is solved. It helps people to concentrate on other questions which still need new ideas

|

Dyppl · Accepted Answer · 2011-05-27 19:12:48Z

12

Well, you are clearing the textbox right before you check if it's empty

/* !! This clears the textbox BEFORE you check if it's empty */
MaterialTextBox.Clear();

HoursNumericUpDown.Value = HoursNumericUpDown.Minimum;
MarkNumericUpDown.Value = MarkNumericUpDown.Minimum;

if (String.IsNullOrEmpty(MaterialTextBox.Text))
{
        MessageBox.Show("Enter Material Name Please.", "Error", MessageBoxButtons.OK,    MessageBoxIcon.Warning);
            //dataGridView1.Rows.Clear();
}

answered May 27, 2011 at 19:12

Dyppl

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1 Comment

sam Over a year ago

yea thanks i noticed this stupid mistake done by me...but after this message show up the datagridview insert new row so is there is a way to remove it or maybe discard the whole inserted row or progress ???

tjg184 · Accepted Answer · 2011-05-27 18:47:51Z

3

Use something such as the following:

if (String.IsNullOrEmpty(MaterialTextBox.Text))

answered May 27, 2011 at 18:47

tjg184

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1 Comment

abhilash Over a year ago

This will not handle the whitespaces

cell-in · Accepted Answer · 2016-11-29 06:46:30Z

2

Try doing the following

if (String.IsNullOrEmpty(MaterialTextBox.Text) || String.IsNullOrWhiteSpace(MaterialTextBox.Text))
    {
        //do job
    }
    else
    {
        MessageBox.Show("Please enter correct path");
    }

Hope it helps

edited Nov 29, 2016 at 6:46

answered Nov 28, 2016 at 5:44

cell-in

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Comments

contactmatt · Accepted Answer · 2011-05-27 18:59:16Z

0

Adding on to what @tjg184 said, you could do something like...

if (String.IsNullOrEmpty(MaterialTextBox.Text.Trim()))

...

answered May 27, 2011 at 18:59

contactmatt

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Comments

Beginner · Accepted Answer · 2013-07-30 09:44:36Z

0

if (MaterialTextBox.Text.length==0)
{
message

}

answered Jul 30, 2013 at 9:44

Beginner

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Comments

DeveloperLV · Accepted Answer · 2020-05-15 12:27:56Z

0

For multiple text boxes - add them into a list and show all errors into 1 messagebox.

// Append errors into 1 Message Box      

 List<string> errors = new List<string>();   

 if (string.IsNullOrEmpty(textBox1.Text))
    {
        errors.Add("User");
    }

    if (string.IsNullOrEmpty(textBox2.Text))
    {
        errors.Add("Document Ref Code");
    }

    if (errors.Count > 0)
    {
        errors.Insert(0, "The following fields are empty:");
        string message = string.Join(Environment.NewLine, errors);
        MessageBox.Show(message, "errors", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        return;
    }

answered May 15, 2020 at 12:27

DeveloperLV

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Comments

Juano · Accepted Answer · 2020-07-22 12:58:58Z

0

Becasue is a TextBox already initialized would be better to control if there is something in there outside the empty string (which is no null or empty string I am afraid). What I did is just check is there is something different than "", if so do the thing:

 if (TextBox.Text != "") //Something different than ""?
        {
            //Do your stuff
        }
 else
        {
            //Do NOT do your stuff
        }

answered Jul 22, 2020 at 12:58

Juano

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