OpenEuphoria

Re: C_func problems...

• Posted by Greg Haberek <ghaberek at gmail.com> Nov 25, 2004
• 569 views

NULL should be 0, not -1

-1 is sent to a C function as #FFFFFFFF and it thinks that's a memory
address (pointer) of a the structure LPSECURITY_ATTRIBUTES. 0, on the
other hand, is an empty memory address.


On Thu, 25 Nov 2004 17:04:10 +1100, Patrick Barnes <mrtrick at gmail.com> wrote:
> 
> Can anybody tell me why the following code has a machine-level
> exception error when run?
> 
> The relevant msdn entry is here:
>
> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/createmutex.asp
> 
> Very frustrating...
> 
> }}}
<eucode>
> constant NULL = -1
> include dll.e
> include machine.e
> constant kernel32 = open_dll("kernel32")
> --HANDLE CreateMutex(
> --  LPSECURITY_ATTRIBUTES lpMutexAttributes,
> --  BOOL bInitialOwner,
> --  LPCTSTR lpName
> --);
> constant xCreateMutex = define_c_func(kernel32, "CreateMutexA",
> {C_POINTER, C_CHAR, C_POINTER}, C_INT   )
> 
> function createMutex(sequence name)
>        atom ret, str
>        str = allocate_string(name)
>        ret = c_func(xCreateMutex, {NULL, 0, str})
>        free(str)
>        return ret
> end function
> 
> ? createMutex("testing")
> </eucode>
{{{

> 
> --
> MrTrick
> 
>