在C＃中检查空指针

Question

I am calling a C function. The function will return a handle. The handle is actually a pointer but the C# program only uses it to call other C functions. The C program will return a C NULL if there was an error. I want the C# program to check if a C NULL was returned.

The "prototype" is as follows:

[DllImport("W:\\Dropbox\\DSI (His)\\Windows Apps\\Debug\\DsiLibrary_CSharp.dll", CharSet = CharSet.Ansi)]
public static extern UIntPtr XBaseGetDefineFile(short fileNum);

The basic idea of the 'if' would be this:

if (XBaseFunctions.XBaseGetDefineFile(900) == null)

I have looked at lots of samples of null pointers but none discuss this topic. So I tried several ideas but to no success.

What I need to know is how to properly construct the 'if' statement.

Answer 1

A null pointer is simply a pointer to the memory address '0'. Therefor:

if (XBaseFunctions.XBaseGetDefineFile(900) == UIntPtr.Zero)