About Global.asax in ASP.NET

• Global.asax is a file in asp.net
• Global.asax file contains all the application level methods.like
•       1.Application_Start 2.Application_End 3.Session_Start 4.Session_End etc..
• Note: When you compile your code for the first time your ASP.NET runtime creates a class corresponding to Global.asax file with the Class name global_asax. This class inherits from HTTP Application class.
• You can see the automatically created class in the C:\Documents and Settings\User\My Documents\Visual Studio 2008\WebSites\ApplicationName\global.asax file.

Adding new Nodes to XML File in C#

1.Create a Dummy xml file with the name Patients.xml in your solution explorer.
    Ex:

 <Patients>
  <Patient type="IP">
    <VistorNum>134</VistorNum>
    <FName>Maha</FName>
    <LName>Veer</LName>
    <Age>89</Age>
    <Sex>Male</Sex>
  </Patient>
</Patients>

 

2.Create the UI to accept data from users.(Write the below code in .aspx page)
   VisitorNum:<asp:TextBox ID="tbVstrNum" runat="server" ></asp:TextBox><br />
    FName:<asp:TextBox ID="tbFName" runat="server" ></asp:TextBox><br />
    LName:<asp:TextBox ID="tbLName" runat="server" ></asp:TextBox><br />
    Age:<asp:TextBox ID="tbAge" runat="server" ></asp:TextBox><br />
    Sex:<asp:TextBox ID="tbSex" runat="server" ></asp:TextBox><br />
    <asp:Button ID="btnInsertPat" Text="AddPatient" runat="server" 
            onclick="btnInsertPat_Click" />
3.Write the below code in code behind's button click method.
    protected void btnInsertPat_Click(object sender, EventArgs e)
    {
        XmlDocument doc = new XmlDocument();
        doc.Load(Server.MapPath("Patients.xml"));
        //Create a New patient node.
        XmlNode nPatient=doc.CreateNode(XmlNodeType.Element,"Patient",null);
        //Create visitornUm,FName,LName,Age,Sex nodes and add 
        //it to Patient Node
        XmlElement eVistNum= doc.CreateElement("VistorNum");
        eVistNum.InnerText = tbVstrNum.Text;
        XmlElement eFName = doc.CreateElement("FName");
        eFName.InnerText = tbFName.Text;
        XmlElement eLName = doc.CreateElement("LName");
        eLName.InnerText = tbLName.Text;
        XmlElement eAge = doc.CreateElement("Age");
        eAge.InnerText = tbAge.Text;
        XmlElement eSex = doc.CreateElement("Sex");
        eSex.InnerText = tbSex.Text;
        nPatient.AppendChild(eVistNum);
        nPatient.AppendChild(eFName);
        nPatient.AppendChild(eLName);
        nPatient.AppendChild(eAge);
        nPatient.AppendChild(eSex);
        //Get the Root Patients Node ref.
        XmlNode root=doc.SelectSingleNode("Patients");
        //Add New patient node to root patient node.
        root.AppendChild(nPatient);
        string sPath = Server.MapPath("Patients.xml");
        doc.Save(sPath);
        //elem.AppendChild(
    }
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Opening My Computer Using ASP.NET

Please use the HTML Input File Control for opening all the available Drives. Just Drag and drop the control
on to the .aspx page and check the result by clicking on the Browse Button.

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How to Encrypt Connection String

For security reasons we need to encrypt the connection strings.
Encrypting and decrypting the connection string is very easy. Follow the Below steps to encrypt the Connection strings.
Encrypt Connection Strings:

• Open visual studio command prompt.
• type the given command  aspnet_regiis -pef  "connectionStrings"  "YourApplicationFullPath where your web.config file is present"  and then press Enter.

Decrypting Connection String:

• aspnet_regiis -pdf  "connectionStrings" "YourApplicationFullPath where your web.config file is present"  and then press Enter.

Note : You need to use pef or pdf only if your website is created as a file system. If Your website is created as a IIS website then use pe or pd for encrypting or decrypting.

is and as operators in C#

is Operator:

• is operator Checks if an object is compatible with a given type 
• An is expression evaluates to true if the provided expression is non-null, and the provided object     can  be cast to the provided type without causing  an exception to be thrown.

as Operator:

• The as operator is used to perform conversions between compatible reference types      
• The as operator is like a cast operation. However, if the conversion is not possible, as returns null instead of raising an exception

Ex:

public class Exam

{

    public string GetSubjectName()

    {

        return "C#";

    }

}

public class UnitTest

{

    public int GetTestNumber()

    {

        return 1;

    }

}

public partial class CSHARPSAMPLES_Keywords : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        Exam e1 = new Exam();

    }

    public void Test(object o)

    {

        if (o is UnitTest)

        {

            UnitTest u = o as UnitTest;

            u.GetTestNumber();

        }

        else if (o is Exam)

        {

            Exam e = o as Exam;

            e.GetSubjectName();

        }

    }

}

Ternary Operators in C#

Ternary operators can be use full when we have only one simple if else condition.
Ternary Operator Syntax:

condition ? first_expression : second_expression;

Ex:

public class TernaryEx
{
    public int GetBigNum(int a, int b)
    {
        return a > b ? a : b;
        //in the above syntax if a is greater than b
        //the above expression returns a else it returns b.
    }
}

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How to show XML Data in the Grid View

• Create a Page with the Name XMLSample.aspx
• Write the Below controls in the .aspx source Page.
• Create an xml file on the desktop with Name Students ( See example xml at the End)

<asp:GridView ID="gvList" runat="server">
        </asp:GridView>
        Path:
        <asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="btnAdd" runat="server" Text="Add" onclick="btnAdd_Click" />

• Write the Below code in the Code behind file

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Xml;

public partial class XMLSample : System.Web.UI.Page 

{

    protected void Page_Load(object sender, EventArgs e)

    {

    }

    protected void btnAdd_Click(object sender, EventArgs e)

    {

        HttpPostedFile hpf=FileUpload1.PostedFile;

        string fName=FileUpload1.PostedFile.FileName;

        System.Data.DataSet ds = new System.Data.DataSet();

        ds.ReadXml(fName);

        gvList.DataSource = ds.Tables[0];

        gvList.DataBind();

        

        

    }

}

Note : Example Xml file.

<Students>
  <Student>
    <id>1312</id>
    <name>123</name>
    <age>123123</age>
  </Student>
  <Student>
    <id>6</id>
    <name>Ashoke</name>
    <age>23</age>
  </Student>
</Students>