32-bit and 64-bit data models

	ILP32	LP64	LLP64	ILP64
char	8	8	8	8
short	16	16	16	16
int	32	32	32	64
long	32	64	32	64
long long	64	64	64	64
size_t	32	64	64	64
pointer	32	64	64	64

x64 는 LLP64, LINUX는 LP64 모델임.

Type name	Type size (32-bit system)	Type size (64-bit system)	Description
ptrdiff_t	32	64	Signed integer type that appears after the subtraction of two pointers. It is used to keep sizes. Sometimes it is used as the result of a function returning the size or -1 if an error occurs.
size_t	32	64	Unsigned integer type. The result of the sizeof() operator. It is used to keep the size or count of objects.
intptr_t, uintptr_t, SIZE_T, SSIZE_T, INT_PTR, DWORD_PTR, etc	32	64	Integer types able to keep the pointer value.
time_t	32	64	Time in seconds.

Mamma