Creates a name for a temporary file
#include <WinAPIFiles.au3>
_WinAPI_GetTempFileName ( $sFilePath [, $sPrefix = ''] )
| $sFilePath | The directory path for the file name. Applications typically specify a period (.) for the current directory. | 
| $sPrefix | [optional] The prefix string. The function uses up to the first three characters of this string as the prefix of the file name. | 
| Success: | The temporary file name. | 
| Failure: | Sets the @error flag to non-zero, call _WinAPI_GetLastError() to get extended error information. | 
Temporary files whose names have been created by this function are not automatically deleted.
Search GetTempFileName in MSDN Library.