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The C and C++ Include Header Files

cat -n /usr/include/x86_64-linux-gnu/bits/wordsize.h

     1	/* Determine the wordsize from the preprocessor defines.  */
     2	
     3	#if defined __x86_64__ && !defined __ILP32__
     4	# define __WORDSIZE	64
     5	#else
     6	# define __WORDSIZE	32
     7	#define __WORDSIZE32_SIZE_ULONG		0
     8	#define __WORDSIZE32_PTRDIFF_LONG	0
     9	#endif
    10	
    11	#define __WORDSIZE_TIME64_COMPAT32 1
    12	
    13	#ifdef __x86_64__
    14	/* Both x86-64 and x32 use the 64-bit system call interface.  */
    15	# define __SYSCALL_WORDSIZE		64
    16	#endif