Limit Char in Textbox Control

Question

5.00/5 (1 vote)

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.NET4.5

This code make my texbox control only can get input char captal 'A'

C#

private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = (e.KeyChar == (char)Keys.A)
}

but how to make my textbox control only can get input char small 'a'
below this code is not work,i can't find any idea or any trick to solve it

C#

private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = (e.KeyChar == (char)Keys.a)
}

anybody can help me?

Posted 17-May-13 21:20pm

Gun Gun Febrianza

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2 solutions

Solution 2

Hi,

Instead of using the Keys enum, use char. So, replace:

C#

private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = (e.KeyChar == (char)Keys.a)
}

with this:

C#

private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = (e.KeyChar == 'a');
}

Hope this helps.

Posted 18-May-13 5:45am

Thomas Daniels

Comments

Gun Gun Febrianza 19-May-13 8:16am

thankyou this is work for me :)

Thomas Daniels 19-May-13 10:26am

You're welcome!

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Mayur Panchal · Accepted Answer · 2013-05-17T21:30:00

Solution 1

You can do something like below :

C#

//Define a list of char, which will store chars to be disabled
List<char> lstdisableChar = new List<char>();

C#

//Assign below event for all the checkboxes, here you have store char in above defined list
//on checked and remove on  uncheck.
private void CheckBox_CheckedChanged(object sender, EventArgs e)
{
    CheckBox chkTmp = sender as CheckBox;

    if (chkTmp.Name == checkBox1.Name)
    {
        if (chkTmp.Checked)
            lstdisableChar.Add('A');
        else 
            lstdisableChar.Remove('A');
    }
    else if (chkTmp.Name == checkBox2.Name)
    {
        if (chkTmp.Checked)
            lstdisableChar.Add('a');
        else
            lstdisableChar.Remove('a');
    }
}

C#

//Handle if list contains key char
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    e.Handled = lstdisableChar.Contains(e.KeyChar);
}

Posted 17-May-13 21:30pm

Mayur Panchal

Updated 17-May-13 23:11pm

v2

Comments

Gun Gun Febrianza 18-May-13 3:54am

sir how to make this code become a method like this

private void disableA()
{
e.Handled = (e.KeyChar == (char)Keys.A)
}

so i can call it another time? but the code in above is not working,..

Mayur Panchal 18-May-13 4:00am

But why you want to call another method ? you can make a condition in KeyPress event though.
What's your condition, when u want to disable 'A' and 'a' ?

Gun Gun Febrianza 18-May-13 4:08am

private void disableA()
{
e.Handled = (e.KeyChar == (char)Keys.A)
}

private void disableB()
{
e.Handled = (e.KeyChar == (char)Keys.B)
}

private void disableC()
{
e.Handled = (e.KeyChar == (char)Keys.C)
}

private void disableD()
{
e.Handled = (e.KeyChar == (char)Keys.D)
}

so in another time i can call the method using checkbox,
if checkbox1.checked = true
{
disableA();
}

if checkbox2.checked = true
{
disableB();
}

can you help me?

Mayur Panchal 18-May-13 4:57am

it's not possible to set e.Handled on checkbox's checkedchanged event.
You have to do some other workaround for that.
I suggest you to maintain disable chars in List<char> when you check on checkboxes and then handle it in keypress event. You need to find in list whether your disable char is present or not.

Mayur Panchal 18-May-13 5:12am

Look at the updated solution above.

Gun Gun Febrianza 19-May-13 8:16am

oke thank you sir :)