Switch Internet Explorer to Offline Mode

I saw a newsgroup post today asking about programmatically (.NET way) switching Internet Explorer to offline mode (checking IE’s File | Work Offline menu item). I posted a small C# code that accomplishes this to the newsgroup. Thought would make a blog entry on it for everyone’s benefit.

NOTE: This code was tested on Windows XP SP2 and Vista RC1.

[DllImport ("wininet.dll")]
private extern static bool InternetSetOption (int hInternet,
int dwOption, ref INTERNET_CONNECTED_INFO lpBuffer, int dwBufferLength); [StructLayout (LayoutKind.Sequential)] struct INTERNET_CONNECTED_INFO { public int dwConnectedState; public int dwFlags; }; private readonly int INTERNET_STATE_DISCONNECTED = 16; private readonly int INTERNET_STATE_CONNECTED = 1; private readonly int ISO_FORCE_DISCONNECTED= 1; private readonly int INTERNET_OPTION_CONNECTED_STATE = 50; void SetIEConnectionMode (bool offline) { INTERNET_CONNECTED_INFO ici = new INTERNET_CONNECTED_INFO (); if (offline) { ici.dwConnectedState = INTERNET_STATE_DISCONNECTED; ici.dwFlags = ISO_FORCE_DISCONNECTED; } else { ici.dwConnectedState = INTERNET_STATE_CONNECTED; } InternetSetOption (0, INTERNET_OPTION_CONNECTED_STATE, ref ici, Marshal.SizeOf (ici)); }
To swich back to online mode, set INTERNET_STATE_CONNECTED to dwConnectedState member of the structure. dwFlags is not required in this case.

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