display a value of the text box when the button is clicked in a web form

Question

I want when the button is clicked a string comes on the textbox based on user selection, I don't know how to do that this is the code:

    protected void Button1_Click(object sender, EventArgs e)
    {

        //DECLARE A STRING VARIABLE 
        String choice = "";
        //LET THE USER SELECT BETWEEN TWO VALUES TO DISPLAY PRICE OF THE BOOK
       Response.Write("<script>choice=window.prompt('Which Currency you want the price display ? 1 : Dollar or 2: Euro');" + "if(choice=='1'){ document.writeln('$22.43');}" + "if(choice=='2') document.write(' 20.55 EUR');" + "</script>");


    }

    protected void TextBox1_TextChanged(object sender, EventArgs e)
    {

    }

Answer 1

Try this:

string yourString = "heyheyhey"; TextBoxName.Text = yourString;

Answer 2

1.Use label and edit text from label1 to Which Currency you want the price display? 1: Dollar or 2: Euro.

2.Use another label in which you want display the currency and name it as lbl_currency.

3.Use a text box and name it as txt_choice.

4.use button name it as btn,double click button and in the click event enter this code.

protected void btn_Click(object sender, EventArgs e)
{

    if(Convert.ToInt32(txt_choice.Text)==1){
     lbl_currency.Text="$22.43";
    }
    else if(Convert.ToInt32(txt_choice.Text)==2){
     lbl_currency.Text="20.55 EUR";
    }
    else{
     MessageBox.Show("Wrong Input");
    }

}

Answer 3

You need to have control called RadioButtonList for selecting your currency then in code behide

protected void btn_Click(object sender, EventArgs e)
{

    if(yourID_RadioButtonList.SelectedValue)=="Something"){
     lbl_currency.Text="Your_Value1";
    }
    else {
     lbl_currency.Text="Your_Value2";
    }
}