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NET App Developer Notes
Bunch of exercises and learning's encountered while developing a Tool for my work. All examples posted as simple console apps. Many of them refer back to stackoverflow learnings. This post is intended for my reference. Try / Catch block and error handling is not included in some cases.
Tip #1 - Reading First Line from a File
Program.cs
using System;
using System.Configuration;
using System.IO;
namespace ServiceExample
{
class Program
{
public static void Main(string[] args)
{
string sourceFileNamePath = ConfigurationManager.AppSettings["sourceFileNamePath"];
string line = "";
int linecount;
Program P = new Program();
line = P.GetLine(sourceFileNamePath, 1);
Console.WriteLine(line);
Console.ReadLine();
}
public string GetLine(string fileName, int lines)
{
using (var sr = new StreamReader(fileName))
{
for (int i = 1; i < lines; i++)
sr.ReadLine();
return sr.ReadLine();
}
}
}
}
App.config entry
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings file="" >
<clear />
<add key="sourceFileNamePath" value="E:\\TestFiles.csv"/>
</appSettings>
</configuration>
Tip #2 - Find Duplicates values in a line using Hash method
using System;
using System.Collections.Generic;
using System.Configuration;
using System.IO;
using System.Linq;
namespace TestExample
{
class Program
{
public static void Main(string[] args)
{
char[] delimiterChars = { ' ', ',', '.', ':', '\t' };
string line = "A A B C D E F G H";
string[] Attributes = line.Split(delimiterChars);
var hash = new HashSet<string>(Attributes);
string[] uniqueAttributes = hash.ToArray();
if (Attributes.Length == uniqueAttributes.Length)
{
Console.WriteLine("No Duplicate Elements present");
}
else
{
Console.WriteLine("Duplicate Elements present");
}
Console.WriteLine(line);
Console.ReadLine();
}
public string GetLine(string fileName, int lines)
{
using (var sr = new StreamReader(fileName))
{
for (int i = 1; i < lines; i++)
sr.ReadLine();
return sr.ReadLine();
}
}
}
}
Tip #3, #4 - Fetching a Single (Scalar) value from DB and Fetching multiple rows
Note - In case of Error add the Assembly refereces to fix them
using System;
using System.Collections;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.IO;
using System.Linq;
namespace TestExample
{
class Program
{
public static void Main(string[] args)
{
Program P = new Program();
P.FetchScalarValue();
P.FetchDBMethod();
}
public int FetchDBMethod()
{
try
{
Console.WriteLine("Fetch Multiple DB Values Example \n");
SqlCommand comm = new SqlCommand();
comm = SetUpConnection();
OpenConnection(comm);
comm.CommandType = CommandType.Text;
comm.CommandText = @"SELECT TOP 10 [CustomerID],[NameStyle],[Title],[FirstName],[MiddleName]
,[LastName],[Suffix],[CompanyName],[SalesPerson],[EmailAddress],[Phone]
,[PasswordHash],[PasswordSalt],[rowguid]
FROM [AdventureWorksLT2008R2].[SalesLT].[Customer]";
SqlDataReader oReader = comm.ExecuteReader();
if (oReader.HasRows)
{
while (oReader.Read())
{
Console.WriteLine(oReader[2].ToString());
Console.WriteLine(oReader[3].ToString());
Console.WriteLine(oReader[4].ToString());
Console.WriteLine(oReader[5].ToString());
Console.WriteLine(oReader[6].ToString());
Console.WriteLine(oReader[7].ToString());
Console.WriteLine(oReader[8].ToString());
Console.WriteLine(oReader[9].ToString());
Console.WriteLine(oReader[10].ToString());
Console.ReadLine();
}
}
else
{
return 0;
}
oReader.Close();
CloseConnection(comm);
return 0;
}
catch (Exception EX)
{
return 1;
}
}
public void FetchScalarValue()
{
try
{
Console.WriteLine("Fetch Single DB Values Example \n");
SqlCommand comm = new SqlCommand();
comm = SetUpConnection();
OpenConnection(comm);
comm.CommandType = CommandType.Text;
comm.CommandText = @"SELECT COUNT(1)
FROM [AdventureWorksLT2008R2].[SalesLT].[Customer]";
Console.WriteLine(comm.ExecuteScalar().ToString());
Console.ReadLine();
}
catch (Exception EX)
{
}
}
public SqlCommand SetUpConnection()
{
string strConn = ConfigurationManager.AppSettings["ConnectionString"];
SqlCommand comm = new SqlCommand();
comm.Connection = new SqlConnection(
strConn);
return comm;
}
public void OpenConnection(SqlCommand comm)
{
comm.Connection.Open();
}
public void CloseConnection(SqlCommand comm)
{
comm.Connection.Close();
}
}
}
App.Config File
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings file="" >
<clear />
<add key="ConnectionString" value="Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=AdventureWorksLT2008R2;Data Source=.\SQLSERVER2008R2" />
</appSettings>
</configuration>
Tip #5 - Best practice use of Try catch Exception handling
I like the stackoverflow question -
Is this a bad practice to catch a non-specific exception such as System.Exception? Why?
Tip #6 - Status check for methods
Narrowly focussed on developing a working code without thinking of making it cleaner and better. Transition from DB to C# this is a good
learning. My learning is best described in stack overflow question -
return status checking
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Happy Learning!!!
