ConfigurationManager read-write appsettings key value pair

usingSystem;usingSystem.Configuration;namespaceconsoleapplication1{classProgram {Static voidMain (string[] args)            {readallsettings (); Readsetting ("Setting1"); Readsetting ("Notvalid"); Addupdateappsettings ("newsetting","May 7,"); Addupdateappsettings ("Setting1","May 8,");        Readallsettings (); }        Static voidreadallsettings () {Try            {                varAppSettings =configurationmanager.appsettings; if(Appsettings.count = =0) {Console.WriteLine ("AppSettings is empty."); }                Else                {                    foreach(varKeyinchAppsettings.allkeys) {Console.WriteLine ("Key: {0} Value: {1}", Key, Appsettings[key]); }                }            }            Catch(configurationerrorsexception) {Console.WriteLine ("Error reading app settings"); }        }        Static voidReadsetting (stringkey) {            Try            {                varAppSettings =configurationmanager.appsettings; stringresult = Appsettings[key]??"Not Found";            Console.WriteLine (result); }            Catch(configurationerrorsexception) {Console.WriteLine ("Error reading app settings"); }        }        Static voidAddupdateappsettings (stringKeystringvalue) {            Try            {                varConfigFile =configurationmanager.openexeconfiguration (Configurationuserlevel.none); varSettings =configFile.AppSettings.Settings; if(Settings[key] = =NULL) {settings.                ADD (key, value); }                Else{Settings[key]. Value=value;                } configfile.save (configurationsavemode.modified);            Configurationmanager.refreshsection (ConfigFile.AppSettings.SectionInformation.Name); }            Catch(configurationerrorsexception) {Console.WriteLine ("Error writing app settings"); }        }    }}

The preceding example assumes that your project has an app. config file as shown below.

Xml

<?xml version= "1.0" encoding= "Utf-8"?><configuration>    <startup>         <supportedruntime version= "v4.0" sku= ". netframework,version=v4.5 "/>    </startup>  <appSettings>    <add key=" Setting1 "value=" May 5, "/>    <add key=" Setting2 "value=" 6 "/>  </appSettings></configuration>

ConfigurationManager read-write appsettings key value pair