How to set focus back to text box C#

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i am creating class to inherit TextBox for Date.

1. on lost focus i am validating the text to check if it is valid date and if not display message and set focus to same text box to prevent user moving out without correcting date.

below line in code gets underline with red

this.Focus;

Error CS0201 Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement

What I have tried:

protected override void OnLostFocus(EventArgs e)
       {
           base.OnLostFocus(e);

           if (this.Text == "")
           {

           }
           else
           {



               if (DateTime.TryParseExact(this.Text, "dd/mm/yyyy",
                                   System.Globalization.CultureInfo.InvariantCulture,
                                   System.Globalization.DateTimeStyles.None,
                                   out DateTime theDate))
               {


               }
               else
               {
                 MessageBox.Show("Invalid Date : Date should be in 'DD/MM/YYYY' format");

                   this.Focus;
               }

           }
       }

Posted 13-Mar-20 22:01pm

pravin9455

Updated 13-Mar-20 22:27pm

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Richard MacCutchan 14-Mar-20 5:24am

Why not use a DatePicker instead of a TextBox?

1 solution

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phil.o · Accepted Answer · 2020-03-13T22:14:00

Solution 1

C#

this.Focus();

Focus is a method of Control class; as such, its calls have to be made with brackets. If you omit the brackets, compiler will search for a property with this name, which it won't find.

Posted 13-Mar-20 22:14pm

phil.o

Comments

pravin9455 14-Mar-20 5:11am

Thanks

i have problem with changing back color also ongotfocus

in below code line Color get underline with red

this.BackColor = Color.red;

Error CS0103 The name 'Color' does not exist in the current context

protected override void OnGotFocus(EventArgs e)
{
base.OnGotFocus(e);
if (this.ReadOnly == true)
{
this.BackColor = Color.red;

}

else
{
this.BackColor = Color.SeaGreen;
}

}

phil.o 14-Mar-20 5:18am

You are missing a using System.Drawing; directive on top of your code file.

pravin9455 14-Mar-20 5:30am

thanks
Got it