How to clear the text of all textBoxes in the form

问题:

private void CleanForm()
{
    foreach (var c in this.Controls)
    {
        if (c is TextBox)
        {
            ((TextBox)c).Text = String.Empty;
        }
    }
}

This method above doesn't work and the controls aren't cleared. It compiles fine, but does nothing.

Any ideas?

回答1:

I like lambda :)

 private void ClearTextBoxes()
 {
     Action<Control.ControlCollection> func = null;

     func = (controls) =>
         {
             foreach (Control control in controls)
                 if (control is TextBox)
                     (control as TextBox).Clear();
                 else
                     func(control.Controls);
         };

     func(Controls);
 }

Good luck!

回答2:

We had a problem like this some weeks before. If you set a breakpoint and have a deep look into this.Controls, the problem reveals it's nature: you have to recurse through all child controls.

The code could look like this:

private void CleanForm()
{
    traverseControlsAndSetTextEmpty(this);
}
private void traverseControlsAndSetTextEmpty(Control control)
{

    foreach(var c in control.Controls)
    {
        if (c is TextBox) ((TextBox)c).Text = String.Empty;
        traverseControlsAndSetTextEmpty(c);
    }
}

回答3:

Your textboxes are probably inside of panels or other containers, and not directly inside the form.

You need to recursively traverse the Controls collection of every child control.

回答4:

private void CleanForm(Control ctrl)
{
    foreach (var c in ctrl.Controls)
    {
        if (c is TextBox)
        {
            ((TextBox)c).Text = String.Empty;
        }

        if( c.Controls.Count > 0)
        {
           CleanForm(c);
        }
    }
}

When you initially call ClearForm, pass in this, or Page (I assume that is what 'this' is).

回答5:

And this for clearing all controls in form like textbox, checkbox, radioButton

you can add different types you want..

private void ClearTextBoxes(Control control)
    {
        foreach (Control c in control.Controls)
        {
            if (c is TextBox)
            {
                ((TextBox)c).Clear();
            }

            if (c.HasChildren)
            {
                ClearTextBoxes(c);
            }


            if (c is CheckBox)
            {

                ((CheckBox)c).Checked = false;
            }

            if (c is RadioButton)
            {
                ((RadioButton)c).Checked = false;
            }
        }
    }

回答6:

I improved/fixed my extension method.

public  static class ControlsExtensions
{
    public static void ClearControls(this Control frm)
    {
        foreach (Control control in frm.Controls)
        {
            if (control is TextBox)
            {
                control.ResetText();
            }

            if (control.Controls.Count > 0)
            {
                control.ClearControls();
            }
        }
    }
}

回答7:

Try this:

var t = Form.Controls.OfType<TextBox>().AsEnumerable<TextBox>();
foreach (TextBox item in t)
{
    item.Text = "";
}

回答8:

Maybe you want more simple and short approach. This will clear all TextBoxes too. (Except TextBoxes inside Panel or GroupBox).

 foreach (TextBox textBox in Controls.OfType<TextBox>())
    textBox.Text = "";

回答9:

You can try this code

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    {


        if(keyData==Keys.C)
        {
            RefreshControl();
            return true;
        }


        return base.ProcessCmdKey(ref msg, keyData);
    }