Out
Keyword in C#
Introduction
Today, in this
article let's play around with one of the interesting and most useful concept in
C#.
Question: What
is out keyword?
In simple terms
"The
out keyword causes arguments to be passed by reference. This is similar to the
ref keyword, except that ref requires that the variable be initialized before
being passed."
Step 1:
Create a new webform project
![pic1.png]()
Step 2:
The
complete code of webform1.aspx looks like this
<%@
Page Language="C#"
AutoEventWireup="true"
CodeBehind="WebForm1.aspx.cs"
Inherits="OutKeywordApp.WebForm1"
%>
<!DOCTYPE
html>
<html
xmlns="http://www.w3.org/1999/xhtml">
<head
id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form2"
runat="server">
<center>
<div>
<table>
<tr>
<td
colspan="2"
align="center">
<asp:Label
ID="Label1"
runat="server"
Text="Out Keyword in C#"
Font-Bold="true"
Font-Size="Large"
Font-Names="Verdana"
ForeColor="Maroon"></asp:Label>
</td>
</tr>
<tr>
<td>
<asp:Label
ID="Label6"
runat="server"
Text="Please Enter
FirstNumber" Font-Size="Large"
Font-Names="Verdana"
Font-Italic="true"></asp:Label>
</td>
<td>
<asp:TextBox
ID="TextBox4"
runat="server"></asp:TextBox>
</td>
</tr>
<tr>
<td>
<asp:Label
ID="Label2"
runat="server"
Text="Please Enter
SecondNumber" Font-Size="Large"
Font-Names="Verdana"
Font-Italic="true"></asp:Label>
</td>
<td>
<asp:TextBox
ID="TextBox1"
runat="server"></asp:TextBox>
</td>
</tr>
<tr>
<td
colspan="2"
align="center">
<asp:Button
ID="Button1"
runat="server"
Text="Addition"
Font-Names="Verdana"
Width="213px"
BackColor="Orange"
Font-Bold="True"
OnClick="Button1_Click"
/>
</td>
</tr>
<tr>
<td
colspan="2"
align="center">
<asp:Button
ID="Button2"
runat="server"
Text="Substraction"
Font-Names="Verdana"
Width="213px"
BackColor="Orange"
Font-Bold="True"
OnClick="Button2_Click"
/>
</td>
</tr>
<tr>
<td
colspan="2"
align="center">
<asp:Button
ID="Button3"
runat="server"
Text="Multiplication"
Font-Names="Verdana"
Width="213px"
BackColor="Orange"
Font-Bold="True"
OnClick="Button3_Click"
/>
</td>
</tr>
<tr>
<td
colspan="2"
align="center">
<asp:Button
ID="Button4"
runat="server"
Text="Division"
Font-Names="Verdana"
Width="213px"
BackColor="Orange"
Font-Bold="True"
OnClick="Button4_Click"
/>
</td>
</tr>
<tr>
<td
colspan="2"
align="center">
<asp:Label
ID="Label5"
runat="server"
Font-Bold="true"
Font-Names="Verdana"></asp:Label>
</td>
</tr>
</table>
</div>
</center>
</form>
</body>
</html>
Step 3:
The
complete code of webform1.aspx.cs looks like this
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
namespace
OutKeywordApp
{
public partial
class WebForm1 : System.Web.UI.Page
{
protected void
Page_Load(object sender,
EventArgs e)
{
TextBox4.Focus();
}
protected void
Button1_Click(object sender,
EventArgs e)
{
double a;
double b;
if (string.IsNullOrEmpty(TextBox4.Text)
|| string.IsNullOrEmpty(TextBox1.Text))
{
Label5.Text =
"Please Enter Some Values";
Label5.ForeColor = System.Drawing.Color.Red;
}
else
{
Label5.Text =
"Addition Result is: " + Add(out
a, out b);
Label5.ForeColor = System.Drawing.Color.Green;
TextBox4.Text
= string.Empty;
TextBox1.Text
= string.Empty;
}
}
protected void
Button2_Click(object sender,
EventArgs e)
{
double a;
double b;
if (string.IsNullOrEmpty(TextBox4.Text)
|| string.IsNullOrEmpty(TextBox1.Text))
{
Label5.Text =
"Please Enter Some Values";
Label5.ForeColor = System.Drawing.Color.Red;
}
else
{
Label5.Text =
"Substraction Result is: " + Sub(out
a, out b);
Label5.ForeColor = System.Drawing.Color.Green;
TextBox4.Text = string.Empty;
TextBox1.Text
= string.Empty;
}
}
protected void
Button3_Click(object sender,
EventArgs e)
{
double a;
double b;
if (string.IsNullOrEmpty(TextBox4.Text)
|| string.IsNullOrEmpty(TextBox1.Text))
{
Label5.Text =
"Please Enter Some Values";
Label5.ForeColor = System.Drawing.Color.Red;
}
else
{
Label5.Text =
"Multiplication Result is: " + Mul(out
a, out b);
Label5.ForeColor = System.Drawing.Color.Green;
TextBox4.Text
= string.Empty;
TextBox1.Text
= string.Empty;
}
}
protected void
Button4_Click(object sender,
EventArgs e)
{
double a;
double b;
if (string.IsNullOrEmpty(TextBox4.Text)
|| string.IsNullOrEmpty(TextBox1.Text))
{
Label5.Text =
"Please Enter Some Values";
Label5.ForeColor = System.Drawing.Color.Red;
}
else
{
Label5.Text =
"Division Result is: " + Div(out
a, out b);
Label5.ForeColor = System.Drawing.Color.Green;
TextBox4.Text
= string.Empty; TextBox1.Text =
string.Empty;
}
}
protected double
Add(out double
a, out double
b)
{
a =
double.Parse(TextBox4.Text);
b =
double.Parse(TextBox1.Text);
return a + b;
}
protected double
Sub(out double
a, out double
b)
{
a =
double.Parse(TextBox4.Text);
b =
double.Parse(TextBox1.Text);
return a - b;
}
protected double
Mul(out double
a, out double
b)
{
a =
double.Parse(TextBox4.Text);
b =
double.Parse(TextBox1.Text);
return a * b;
}
protected double
Div(out double
a, out double
b)
{
a =
double.Parse(TextBox4.Text);
b =
double.Parse(TextBox1.Text);
return a / b;
}
}
}
Step 4:
The
output of the application looks like this
![Output2.png]()
Step 5:
The
addition operation output of the application looks like this
![Output3.png]()
I hope this
article is useful for you ...I look forward for your comments and
feedback....Thanks Vijay Prativadi