C#

Dim row As DataRow
            'Loop through the datatable's rows
            For Each row In dt.Rows
                'Newline between the previous row and the next row
                sw.Write(vbNewLine)

                Dim column As New DataColumn()
                'Loop through each column and write the cell the the stringwriter
                For Each column In dt.Columns
                    'If the cell isn't empty write it, else write an empty cell
                    If Not row(column.ColumnName) Is Nothing Then
                        'WK Old code sw.Write(row(column).ToString().Trim() + vbTab)
                        'WK new 10/03/2019 
                        'To fix Marsha issue where preceding zero is truncated when export to Excel is processed. 
                        'This line of code enables the SQL query to return the numbers as unchanged strings, not numbers
                        sw.Write("=""" & row(column).ToString().Trim() & """" & vbTab)
                    Else
                        sw.Write(String.Empty + vbTab)
                    End If
                Next column
            Next row

static bool AreEqual(string str1, string str2)
{
    var compareInfo = CultureInfo.InvariantCulture.CompareInfo;
    bool result = compareInfo.IndexOf(str1, str2, CompareOptions.IgnoreNonSpace) > -1;
    return result;
}

bool compare1 = AreEqual("آبی","آبی");  //true, It's Okay.
bool compare2 = AreEqual("آبی", "ابی"); //true. It's Okay.
bool compare3 = AreEqual("آبی", "آب‌ی"); //true. This is not what I want. It should return false
bool compare4 = AreEqual("آبی", "اب‌ی"); //true. This is not what I want. It should return false.

XDocument doc = XDocument.Load(@"C:\Work\stores.xml");

            var xpath = "//store/Color[text()]" + textBox2.Text;

            var result = ((IEnumerable)doc.XPathEvaluate(xpath)).Cast<XElement>().FirstOrDefault();
            textBox1.Text = result.Value;

<pre><stores>
	<store rollNumer="170">
	    <Name>Jonh</Name>
            <Color>Pink</Color>
	    <Sell>Sugar</Sell>
	</store>

	<store rollNumer="120">
	    <Name>Tedy</Name>
            <Color>Brown</Color>
	    <Sell>Rice</Sell>
	</store>

</stores>

var query = (from r1 in dtMappedSectionNotEmpty.AsEnumerable()
                                 join r2 in dtData.AsEnumerable()
                                 on r1.Field<string>("Row").Trim().ToUpper() equals r2.Field<string>("RowCoordinate").Trim().ToUpper()
                                 join r3 in _Periods.AsEnumerable()
                                 on r2.Field<string>("StandardDate").Replace("A", string.Empty).Replace("E", string.Empty).Trim().ToUpper() equals r3.Replace("A", string.Empty).Replace("E", string.Empty).Trim().ToUpper()
                                 where r1.Field<string>("Tab").Trim().ToUpper() == strTab.Trim().ToUpper()
                                 select new BrokerData
                                 {
                                     RowNumber = r1.Field<string>("Row") ?? "0",
                                     TabName = r1.Field<string>("Matched Section") ?? "",
                                     StandardDate = r3.ToString(),
                                     BRTab = r1.Field<string>("Tab") ?? "",
                                     BRLineItem = r1.Field<string>("Broker Items") ?? "",
                                     Action = r1.Field<string>("Action") ?? "",
                                     StandardLineItem = r1.Field<string>("Matched Items") ?? "",
                                     StandardValue =r2.Field<string>("LineItemDateValue") ?? ""
                                 }).ToList();

using System;
using System.Globalization;

namespace _1002
{
    class Program
    {
        static void Main(string[] args)
        {
            double R = Convert.ToDouble(Console.ReadLine());
            double A = Math.PI * Math.Pow(R, R);
            Console.WriteLine("A = " +A.ToString("F4",CultureInfo.InvariantCulture));
           // Console.ReadLine();
        }
    }
}