detect un-english formats

Question

i am working with a winform application , and in the richbox_textchange i would like to detect whether the entered text is English or not because if it is english i`ll perform LeftToRight typing else RightToLeft typing .

I used that code :

    private void richTextBox1_TextChanged(object sender, EventArgs e)
    {
        if (CultureInfo.CurrentCulture.TextInfo.IsRightToLeft)
        {
            label1.Text = "RTL";
        }
        else
        {
            label1.Text = "LTR";
        }
    }

but i always get : LTR only , label1 never change text to RTL even if i typed arabic !!!

EDIT : ANSWERED !!

Firstly Thanks to everybody for helping me here and especially Oded , here is the solution i could figure out

    private void richTextBox1_TextChanged(object sender, EventArgs e)
    {
        if (InputLanguage.CurrentInputLanguage.Culture.TextInfo.IsRightToLeft)
        {
            label1.Text = "RTL";
        }
        else
        {
            label1.Text = "LTR";
        }
    }

Answer 1

You need to add the correct namespace to the top of your class:

using System.Globalization;

At this point the CultureInfo and TextInfo classes will be available directly.

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Update:

It appears that you are trying to find out the current input language. Take a look at the InputLanguage class and its methods. It is in the System.Windows.Forms namespace.

InputLanguage.CurrentInputLanguage.Culture.TextInfo.IsRightToLeft