Clear all TextBoxes texts

Question

I have a tabControl that contains many textBoxes, I want to add a button to clear all textBoxes's texts at once, I tried this code:

private void ClearButton_Click(object sender, EventArgs e)
{
    foreach (TextBox t in tabControl1.SelectedTab.Controls)
    {
        t.Clear();
    }
}

But this code doesn't work, i got this error message :

Unable to cast object of type 'System.Windows.Forms.Button' to type 'System.Windows.Forms.TextBox

What is wrong in this code?

Ok thanks you i tried some solutions before i asked here but it doesn't work for me — user4374239, Dec 23 '14 at 13:28

score 4 · Answer 1 · answered Dec 23 '14 at 13:23

4

You're trying to iterate through every Control, some of which are not TextBox controls.

You can use OfType to specify which controls you're interested in, instead:

foreach (TextBox t in tabControl1.SelectedTab.Controls.OfType<TextBox>())
{
    t.Clear();
}

answered Dec 23 '14 at 13:23

Grant Winney

65,241
13
115
165

i like that! :) – Stefan Woehrer Dec 23 '14 at 13:24
It doesn't work for me i tried before and i got an error message – user4374239 Dec 23 '14 at 13:30
This is the error message: Impossible d'activer les contraintes. Une ou plusieurs lignes contiennent des valeurs qui violent les contraintes de type non null, unique ou de clé externe – user4374239 Dec 23 '14 at 13:33
But when i remove this code my application runs without errors, what is the relation between this code and the violation of non null, unique or foreign key constraints ???? – user4374239 Dec 23 '14 at 13:47

score 2 · Answer 2 · answered Dec 23 '14 at 13:23

2

you get all controls (not only the TextBoxes) in the foreach loop

try something like this:

foreach (Control t in tabControl1.SelectedTab.Controls)
{
    if(t is TextBox)
        ((TextBox)t).Clear();
}

answered Dec 23 '14 at 13:23

Stefan Woehrer

680
4
12

Same here. It doesn't work for me i tried before and i got an error message – user4374239 Dec 23 '14 at 13:31

score 2 · Accepted Answer · answered Dec 23 '14 at 13:25

Try this code:

void ClearTextBoxes(Control parent)
{
    foreach (Control child in parent.Controls)
    {
        TextBox textBox = child as TextBox;
        if (textBox == null)
            ClearTextBoxes(child);
        else
            textBox.Text = string.Empty;
    }
}

private void ClearButton_Click(object sender, EventArgs e)
{
    ClearTextBoxes(tabControl1.SelectedTab);
}

score 0 · Answer 4 · answered Dec 23 '14 at 13:24

Not all controls are textboxes. Do it this way:

private void ClearButton_Click(object sender, EventArgs e)
{
    foreach (var control in tabControl1.SelectedTab.Controls)
    {
        if(control is TextBox)
        {
             TextBox t = (TextBox)control;
             t.Clear();
             // or short:
             // ((TextBox) control).Clear();
        }
    }
}

Clear all TextBoxes texts

4 Answers4