OpenEuphoria

2. Re: GetLastError

• Posted by Daniel Berstein <daber at PAIR.COM> Dec 23, 1998
• 313 views

At 01:20 p.m. 23-12-98 , you wrote:
>I've noticed in the wininet.dll documentation that there is a general
>win32 function called GetLast Error which gives details of why a
>particular function has not succeeded.
>
>Has anybody got any Euphoria code that accesses GetLastError and gives
>details of the errors.


GetLastError can be found on KERNEL32.DLL. Use the Win32 demos to
understand how to link a DLL function.

Here the reference for GetLastError from Windows SDK:

The GetLastError function returns the calling thread's last-error code
value. The last-error code is maintained on a per-thread basis. Multiple
threads do not overwrite each other's last-error code.

DWORD GetLastError(VOID)


Parameters

This function has no parameters.

Return Values

The return value is the calling thread's last-error code value. Functions
set this value by calling the SetLastError function. The Return Value
section of each reference page notes the conditions under which the
function sets the last-error code.

Remarks

You should call the GetLastError function immediately when a function's
return value indicates that such a call will return useful data. That is
because some functions call SetLastError(0) when they succeed, wiping out
the error code set by the most recently failed function.
Most functions in the Win32 API that set the thread's last error code value
set it when they fail; a few functions set it when they succeed. Function
failure is typically indicated by a return value error code such as FALSE,
NULL, 0xFFFFFFFF, or -1. Some functions call SetLastError under conditions
of success; those cases are noted in each function's reference page.

Error codes are 32-bit values (bit 31 is the most significant bit). Bit 29
is reserved for application-defined error codes; no system error code has
this bit set. If you are defining an error code for your application, set
this bit to one. That indicates that the error code has been defined by an
application, and ensures that your error code does not conflict with any
error codes defined by the operating system.
To obtain an error string for operating system error codes, use the
FormatMessage function. For a complete list of error codes, see the WINNT.H
header file in the Win32 SDK.


Regards,
        Daniel   Berstein
        daber at pair.com