C# Signature:
[DllImport("Shlwapi.dll", SetLastError=true, CharSet = CharSet.Auto)]
static extern uint AssocQueryString(AssocF flags, AssocStr str, string pszAssoc, string pszExtra,
[Out] StringBuilder pszOut, ref uint pcchOut);
VB Signature:
<DllImport("Shlwapi.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function AssocQueryString(ByVal flags As UInteger, ByVal str As UInteger, ByVal pszAssoc As String, _
ByVal pszExtra As String, ByVal pszOut As Text.StringBuilder, ByRef pcchOut As UInteger) As UInteger
End Function
User-Defined Types:
[Flags]
enum AssocF : uint
{
None = 0,
Init_NoRemapCLSID = 0x1,
Init_ByExeName = 0x2,
Open_ByExeName = 0x2,
Init_DefaultToStar = 0x4,
Init_DefaultToFolder = 0x8,
NoUserSettings = 0x10,
NoTruncate = 0x20,
Verify = 0x40,
RemapRunDll = 0x80,
NoFixUps = 0x100,
IgnoreBaseClass = 0x200,
Init_IgnoreUnknown = 0x400,
Init_FixedProgId = 0x800,
IsProtocol = 0x1000,
InitForFile = 0x2000,
}
enum AssocStr
{
Command = 1,
Executable,
FriendlyDocName,
FriendlyAppName,
NoOpen,
ShellNewValue,
DDECommand,
DDEIfExec,
DDEApplication,
DDETopic,
InfoTip,
QuickTip,
TileInfo,
ContentType,
DefaultIcon,
ShellExtension,
DropTarget,
DelegateExecute,
SupportedUriProtocols,
Max,
}
Alternative Managed API:
Do you know one? Please contribute it!
Notes:
Also see http://www.pinvoke.net/default.aspx/shell32.findexecutable (though this method is preferred, see http://visualstudiomagazine.com/articles/2009/10/13/finding-an-associated-executable.aspx).
Tips & Tricks:
Please add some!
Sample Code:
static string AssocQueryString(AssocStr association, string extension)
{
uint length = 0;
uint ret = AssocQueryString(AssocF.None, association, extension, null, null, ref length);
if (ret != 1) //expected S_FALSE
{
throw new InvalidOperationException("Could not determine associated string");
}
var sb = new StringBuilder((int)length); //(length-1) will probably work too as null termination is added
ret = AssocQueryString(AssocF.None, association, extension, null, sb, ref length);
if (ret != 0) //expected S_OK
{
throw new InvalidOperationException("Could not determine associated string");
}
return sb.ToString();
}
