????????Щ?????У????????????????????????????????????????????????????????????????????API????????

????1. ????????

[DllImport("wininet.dll")]
private extern static bool InternetGetConnectedState( out int connectionDescription?? int reservedValue ) ;

????2. ???????

????????:

????connectionDescription : ???????

????reservedValue : ?????

?????????:

????true: On Line

????false: Off Line

????3. ???÷???

????a. ??????????code??????System.Runtime.InteropServices?????????б??????

????b. ??????????? int I = 0;

????c. ????bool state = InternetGetConnectedState(out I??0);

????4.???????????:

using System.Runtime.InteropServices;

namespace internet
{
public class Class1
{
[DllImport("wininet.dll")]
private extern static bool InternetGetConnectedState( out int connectionDescription?? int reservedValue ) ;
public Class1(){}
private bool IsConnected()
{
int I=0;
bool state = InternetGetConnectedState(out I??0);
return state;
}
}

????}