how to write connection string app.config in c#

Application Configuration File.

Open the file and it will be like this (without the key setting, that is my default setting I added to the file) :

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

  <connectionStrings >

    <add name ="DbConnection" connectionString ="Data Source=USER-PC;Initial Catalog=CategoricalClustering;User Id=sa;Password=home;" providerName ="System.Data.SqlClient"/>

  </connectionStrings>

</configuration>

Then in code, we need the assembly we need to manage the configuration file:

1	using System.Configuration;

Actually is very easy, to read a configuration just do this:

        string conString = ConfigurationManager.ConnectionStrings["DbConnection"].ConnectionString;