The difference between int and long

The data model determines the correspondence between the basic data type and the data width in C language. The 32-bit model we use is called ILP32, while 64-bit models have three kinds: LP64, LLP64, and ILP64. In a 64-bit model, the pointer must be 64-bit, but the width of int and long is defined differently in different data types. As the following table:

DataType	LP32	ILP32	LLP64	LP64	ILP64
Char	8	8	8	8	8
Short	16	16	16	16	16
Int	16	32	32	32	64
Long	32	32	32	64	64
Long Long	64	64	64	64	64
Pointer	32	32	64	64	64

The former DOS is supposed to be LP32; now Windows 32 and Linux 32 are ILP32; in the upcoming 64bits world, the Windows x64 version uses the LLP64 model, LINUX64 uses the LP64 model, When you compile with GCC you can specify that-m32 be compiled according to the ILP32 model.

The pointer size is associated with the machine word length. For compatibility, when writing C code, declare a 32bit integer with int, and declare a 64bit integer with a long long.

According to POSIX, the correct format string for an integral type is:

Sign	Char	Short	Int	Long	Long Long
Signed	%hhd	%hd	%d	%ld	%lld
Unsigned	%hhu	%hu	%u	%lu	%llu

The difference between int and long