Read input from text field, do calculation then output to the save page (C#) : Text input « HTML Controls « ASP.NET Tutorial






  1. ASP.NET Tutorial
  2. HTML Controls
  3. Text input
File: Default.aspx


<%@ Page Language="C#" AutoEventWireup="true"
    CodeFile="Default.aspx.cs" Inherits="CurrencyConverter" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
 "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>Currency Converter</title>
  </head>
  <body>
    <form ID="Form1" method="post" runat="server">
        <div>
        Convert:
        <input type="text" ID="US" runat="server"/>U.S. dollars to
        <select ID="Currency" runat="server" />
        <br /><br />
        <input type="submit" value="OK" ID="Convert" runat="server" OnServerClick="Convert_ServerClick" />
        <input type="submit" value="Show Graph" ID="ShowGraph" runat="server" OnServerClick="ShowGraph_ServerClick" />
        <br /><br />
        <img ID="Graph" alt="Currency Graph" scr="" runat="server" />
        <br /><br />
        <div style="font-weight: bold" ID="Result" runat="server"></div>
      </div>
    </form>
  </body>
</html>


File: Default.aspx.cs

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

public partial class CurrencyConverter : System.Web.UI.Page
{
  protected void Page_Load(Object sender, EventArgs e)
  {
    if (this.IsPostBack == false)
    {
      Currency.Items.Add(new ListItem("Euros", "0.5"));
      Currency.Items.Add(new ListItem("Japanese Yen", "100"));
      Currency.Items.Add(new ListItem("Canadian Dollars", "2"));
    }
    Graph.Visible = false;
  }
    protected void Convert_ServerClick(object sender, EventArgs e)
    {
        decimal amount;
        bool success = Decimal.TryParse(US.Value, out amount);
        if (success)
        {
            ListItem item = Currency.Items[Currency.SelectedIndex];

            decimal newAmount = amount * Decimal.Parse(item.Value);
            Result.InnerText = amount.ToString() + " U.S. dollars = ";
            Result.InnerText += newAmount.ToString() + " " + item.Text;
        }
        else
        {
            Result.InnerText = "The number you typed in was not in the correct format. ";
            Result.InnerText += "Use only numbers.";
        }
    }

    protected void ShowGraph_ServerClick(object sender, EventArgs e)
    {
        Graph.Src = "Pic" + Currency.SelectedIndex.ToString() + ".png";
        Graph.Visible = true;
    }
}








4.15.Text input
4.15.1.Set value to html:textbox in page load event (VB.net)
4.15.2.Read input from text field, do calculation then output to the save page (C#)
4.15.3.TextBox server changed event