Rank DataTable with LINQ C# Example

C# > LINQ > Rank

Example: Using LINQ to implement RANK function with DataTable.

using System;

using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication3

{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public  DataTable RankDt(DataTable dt, string fld)
        {
            var rankDt = (from row in dt.AsEnumerable()
                            orderby row.Field<int>(fld) descending
                            select row).CopyToDataTable();

            rankDt.Columns.Add("Rank");

            int rank = 1;
            for (int i = 0; i < rankDt.Rows.Count - 1; i++)
            {
                rankDt.Rows[i]["Rank"] = rank;
                if (rankDt.Rows[i][fld].ToString() != rankDt.Rows[i + 1][fld].ToString())
                    rank++;
            }
            rankDt.Rows[rankDt.Rows.Count - 1]["Rank"] = rank;
            return rankDt;
        }

        private void Form1_Load(object sender, EventArgs e)

        {
            DataSet ds = new DataSet();
            ds.Tables.Add("Product");
            DataTable dt = ds.Tables[0];
            dt.Columns.Add("name", typeof(string));
            dt.Columns.Add("quantity", typeof(Int32));
 
            DataRow dr = dt.NewRow();
            dr[0] = "Product 1" ;
            dr[1] = 500;
            dt.Rows.Add(dr);
            dr = dt.NewRow();

            dr[0] = "Product 2";

            dr[1] = 500;
            dt.Rows.Add(dr);

            dr = dt.NewRow();

            dr[0] = "Product 3";
            dr[1] = 50;
            dt.Rows.Add(dr);

            dr = dt.NewRow();

            dr[0] = "Product 4";
            dr[1] = 100;
            dt.Rows.Add(dr);

            dataGridView1.DataSource = RankDt(dt, "quantity");

        }
     }
}

 

Visual Basic Statements

VB.NET > Statements

AddHandler	Call	Class	Const
Continue	Declare	Delegate	Dim
Do...Loop	Else	End	End
Enum	Erase	Error	Event
Exit

RaiseEvent	ReDim	REM	RemoveHandler
Resume	Return	Select...Case	Set
Stop	Structure	Sub	SyncLock
Then	Throw	Try...Catch...Finally	Using
While...End While	With...End With	Yield

Generics and Arrays Example in C#

C# > Generics > Generics and Arrays

Example: Use a single generic method that takes an IList<T> input parameter and iterate through both a list of integers and an array of string.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication2

{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)

        {
            string[] str = { "0", "1", "2", "3", "4" };
            List<int> intL = new List<int>();
            for (int x = 0; x < 5; x++)
            {
                intL.Add(x);
            }
            ProcessList<string>(str);
            ProcessList<int>(intL);
        }
        static void ProcessList<T>(IList coll)
        {
            foreach (T item in coll)
            {
                MessageBox.Show(item.ToString());
            }
        }
    }
}

Form VB.NET

VB.NET > Form

Form

Is a representation of any window displayed in an application.

Type

• standard
• tool
• borderless
• floating

Example

Create dialog box in runtime

Dim form1 As New Form()

Dim btnYes As New Button()

Dim btnNo As New Button()
btnYes.Text = "Yes"
btnYes.Location = New Point(5, 5)
btnNo.Text = "No"
btnNo.Location = New Point(btnYes.Left, btnYes.Top + 30)

form1.Controls.Add(btnYes)

form1.Controls.Add(btnNo)

form1.Text = "Confirm Dialog Box"

form1.FormBorderStyle = FormBorderStyle.FixedDialog
form1.MaximizeBox = False
form1.MinimizeBox = False
form1.AcceptButton = btnYes
form1.CancelButton = btnNo
form1.StartPosition = FormStartPosition.CenterScreen

form1.ShowDialog()

Object-Oriented Programming VB.NET

VB.NET > Object-Oriented Programming VB.NET

Visual Basic .NET has been entirely rewritten to be fully object-oriented and everything in Visual Basic .NET can be treated as an object.

OOP language:

• Abstraction
• Encapsulation
• Polymorphism
• Inheritance

Examplea

• Abstract class employee 
• Class with events

System Namespace VB.NET

VB.NET > System namespace

System namespace in VB.NET contains fundamental classes and base classes.

String

•  Concat

Create CDATA section XML C#

C# > XML > XmlDocument > CreateCDataSection

CreateCDataSection creates an XmlCDataSection.
CDATA is a section used to quote or escape blocks of text to keep that text from being interpreted as markup language.

Example:

XmlDocument doc = new XmlDocument();
doc.LoadXml("<product ID='1'></ product>");

//Create a CData section

XmlCDataSection CData;
CData = doc.CreateCDataSection("Size is 10/55");

//Add the new node to the document
XmlElement root = doc.DocumentElement;
root.AppendChild(CData);
doc.Save("C:\\Products.xml");

Result:

<product ID="1">

  <![CDATA[Size is 10/55]]>
</product>

Short type C# Example

C# > Types > short

The short keyword is an integral type.
Range: -32768 to 32767
Size: Signed 16-bit integer

Example:

short k = 32767; // ok
k = 32768; // Error Constant value '32768' cannot be converted to a 'short'

Struct in C# Example

C# > Types > Struct

A struct type is a value type and is typically used for representing lightweight objects (color, zip, point).

• cannot inherit from another struct or class
• can be instantiated without using a new operator.
• can implement an interface
• can contain fields, constructors, methods, operators and events, but
• if many members are required  you should make your type a class instead

Note:  Struct might be more efficient than a class in some scenarios. Using array of thousand of objects will be allocate more memory for referencing each object, so in this case, a struct would is more efficient and less expensive.






Example

        public struct strColor
        {
            public int r, g, b;
            public strColor(int p1, int p2, int p3)
            {
                r = p1;
                g = p2;
                b = p3;
            }
        }

       // Initialize using default and parameterized constructor

       strColor color1 = new strColor();
       strColor color2 = new strColor(10, 20, 30);

      // Declare object. It creates object without using the new  operator

       strColor color;

      //Initialize

       color.r = 10;
       color.g = 20;
       color.b = 30;