On 06/26/14 06:05, Shuai Meng wrote: > In wine source code, NULL is defined as 0 in > file dlls/windowscodecs/ungif.h, line 66. I have tried to write like this: > 1260 if(V_VT(arg) == VT_NULL) { > 1261 V_VT(res) = VT_NULL; > 1262 V_NULL(res) = NULL; > 1263 } Hint: there already is return_null helper. Jacek