C #. Net write to app. config

Today I wrote a Windows exampleProgram, I am depressed enough. I haven't been in touch for too long. Write down a little gadgets for future reference.
I will not go into details when reading app. config.
It is said that Microsoft does not recommend that we write app. config dynamically, but it is inevitable that some people write app. config.
In fact, app. config is an XML file. Find the location, read it, modify it, and save it.
Important: the app. config is not running in the original directory, and the name has changed. Therefore, you must write the file at runtime During writing.
CodeAs follows:
 

/**/ ///   <Summary>
/// Set the value of a key in APP. config.
///   </Summary>
///   <Param name = "appkey"> Key </Param>
///   <Param name = "appvalue"> Value </Param>
Public Void Setvalue ( String Appkey, String Appvalue)
{
Xmldocument xdoc =   New Xmldocument ();

// The configuration file is in the program directory.
Xdoc. Load (application. startuppath +   " File: // mailsender.exe. config/ " );
Xmlnode xnode;
Xmlelement xelem1;
Xmlelement xelem2;
Xnode = Xdoc. selectsinglenode ( " // Appsettings " );
Xelem1 = (Xmlelement) xnode. selectsinglenode ( " // Add [@ key =' "   + Appkey +   " '] " );
If (Xelem1 ! =   Null )
{
Xelem1.setattribute ("Value", Appvalue );
}
Else
{
Xelem2 = Xdoc. createelement ( " Add " );
Xelem2.setattribute ( " Key " , Appkey );
Xelem2.setattribute ( " Value " , Appvalue );
Xnode. appendchild (xelem2 );
}
Xdoc. Save (application. startuppath +   " File: // mailsender.exe. config/ " );
}

 

 

In practice, you can simply change mailsender.exe.configto another (projectname.exe. config). After compilation, you can find it in debug. Haha
Note: Most of the Code comes from the network, and others are your own experiences. Thank you for your support.