C# Signature:

/// <summary>
/// The URLMON library contains this function, URLDownloadToFile, which is a way
/// to download files without user prompts.  The ExecWB( _SAVEAS ) function always
/// prompts the user, even if _DONTPROMPTUSER parameter is specified, for "internet
/// security reasons".  This function gets around those reasons.
/// </summary>
/// <param name="pCaller">Pointer to caller object (AX).</param>
/// <param name="szURL">String of the URL.</param>
/// <param name="szFileName">String of the destination filename/path.</param>
/// <param name="dwReserved">[reserved].</param>
/// <param name="lpfnCB">A callback function to monitor progress or abort.</param>
/// <returns>0 for okay.</returns>
[DllImport("urlmon.dll", CharSet=CharSet.Auto, SetLastError=true)]
static extern Int32 URLDownloadToFile(
    [MarshalAs(UnmanagedType.IUnknown)] object pCaller,
    [MarshalAs(UnmanagedType.LPWStr)] string szURL,
    [MarshalAs(UnmanagedType.LPWStr)] string szFileName,
    Int32 dwReserved,
    IntPtr lpfnCB);
// This version maps HRESULT to exception:
[DllImport("urlmon.dll", CharSet=CharSet.Auto, PreserveSig=false)]
private static extern void URLDownloadToFile(
    [MarshalAs(UnmanagedType.IUnknown)] object pCaller,
    [MarshalAs(UnmanagedType.LPTStr)] string szURL,
    [MarshalAs(UnmanagedType.LPTStr)] string szFileName,
    Int32 dwReserved,
    IntPtr lpfnCB);

VB Signature:

Declare Function URLDownloadToFile Lib "urlmon.dll" (TODO) As TODO

User-Defined Types:

None.

Notes:

This function does not prompt user for file location, as does ExecWB (even when you specify DONTPROMPT), and it does not return until file transfer finishes or fails.

http://www.pinvoke.net/default.aspx/urlmon/URLDownloadToFile%20.html

Tips & Tricks:

Please add some!

Sample Code:

    int response = URLDownloadToFile( null, urlStr, fileToStoreStr, 0, IntPtr.Zero );
    // For the second version:
    URLDownloadToFile(IE as SHDocVw.IWebBrowser2, urlStr, fileToStoreStr, 0, IntPtr.Zero );

Alternative Managed API:

Do you know one? Please contribute it!

In VB.Net it's very simple to download a file (use asynchronous pattern from C# example if needed):

    If (My.Computer.Network.IsAvailable) Then
        My.Computer.Network.DownloadFile("http://www.pinvoke.net/", "C:\Temp\pinvoke.htm")
    Else
        MsgBox("Network not found!")
    End If

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