这些数据类型是 C99 中定义的，具体定义在：/usr/include/stdint.h    ISO C99: 7.18 Integer types <stdint.h>

1 /* There is some amount of overlap with 
     
       as known by inet code */ 2 #ifndef __int8_t_defined 3 # define __int8_t_defined 4 typedef signed char             int8_t;  5 typedef short int               int16_t; 6 typedef int                     int32_t; 7 # if __WORDSIZE == 64 8 typedef long int                int64_t; 9 # else10 __extension__11 typedef long long int           int64_t;12 # endif13 #endif14 15 /* Unsigned.  */16 typedef unsigned char           uint8_t;17 typedef unsigned short int      uint16_t;18 #ifndef __uint32_t_defined19 typedef unsigned int            uint32_t;20 # define __uint32_t_defined21 #endif22 #if __WORDSIZE == 6423 typedef unsigned long int       uint64_t;24 #else25 __extension__26 typedef unsigned long long int  uint64_t;27 #endif
     

格式化输出：

unit64_t     %llu   

unit32_t     %u

unit16_t    %hu