C:\test>size_t.exe
_WIN64 is not defined
MAX: 64
size_t    is 4 bytes
int       is 4 bytes
long      is 4 bytes
long long is 8 bytes
UV        is 4 bytes
IV        is 4 bytes
STRLEN    is 4 bytes

C:\test>size_t.exe
_WIN64 is  defined
MAX: 64
size_t    is 8 bytes
int       is 4 bytes
long      is 4 bytes
long long is 8 bytes
UV        is 8 bytes
IV        is 8 bytes
STRLEN    is 8 bytes