How do I call win32 dll from .NET frame work? say kernal32.dll

[Guest]

hi all
How do I call win32 dll from .NET frame work? say kernal32.dll from .NET framework. (from C# and VB)
I heard that we have to use (RCW) Runtime Callable Wrapper for calling COM Components from .NET framework. but what about win32 dll
regards
Balamurali C

 

[Morten Wennevik]

Hi Balamurali C,

You use the DllImport attribute to create a method name you use internally in your code. Using the method name with the DllImport will forward the information to the dll as if you called it directly. Do a search for DllImport to see how it can be used.

[beware of wrapping on this link]
http://msdn.microsoft.com/library/e...teropServicesDllImportAttributeClassTopic.asp

 

[Guest]

Hi Morten Wennevik
This is very helpful to me . Thanks

Regards
Balamurali C

 

[Shell D00d]

It's easy... just declare the win32 function in your application with
the attribute DllImport. Then you can call it like you would any other
method in your code. The framework will take care of marshalling the
call and any parameters to/from your application and the foreign dll.

This is how you would do it in C#:


// First you delcare the function that you want to call
// This should be done at class level
[DllImport("kernel32.dll")]
private static extern bool GetDiskFreeSpaceEx(string directory, ref
long UserSpaceFree, ref long TotalUserSpace, ref long TotalFreeSpace);

protected void SomeMethod()
{
bool ReturnedValue = GetDiskFreeSpaceEx(myExtractRoot, ref
myUserSpaceFree, ref myTotalUserSpace, ref myTotalFreeSpace);
}

In some cases, you may have to specify how you want the parameters to
be marshalled. This will be especially true when you need to send
structs. You can refer to MSDN on how to specify the marshalling
attributes. In most cases, like above, it simply works with no
problems.