std.stdint
D constrains integral types to specific sizes. But efficiency of different sizes varies from machine to machine, pointer sizes vary, and the maximum integer size varies. stdint offers a portable way of trading off size vs efficiency, in a manner compatible with the stdint.h definitions in C.The exact aliases are types of exactly the specified number of bits. The at least aliases are at least the specified number of bits large, and can be larger. The fast aliases are the fastest integral type supported by the processor that is at least as wide as the specified number of bits.
The aliases are:
Exact Alias  Description  At Least Alias  Description  Fast Alias  Description 

int8_t  exactly 8 bits signed  int_least8_t  at least 8 bits signed  int_fast8_t  fast 8 bits signed 
uint8_t  exactly 8 bits unsigned  uint_least8_t  at least 8 bits unsigned  uint_fast8_t  fast 8 bits unsigned

int16_t  exactly 16 bits signed  int_least16_t  at least 16 bits signed  int_fast16_t  fast 16 bits signed 
uint16_t  exactly 16 bits unsigned  uint_least16_t  at least 16 bits unsigned  uint_fast16_t  fast 16 bits unsigned

int32_t  exactly 32 bits signed  int_least32_t  at least 32 bits signed  int_fast32_t  fast 32 bits signed 
uint32_t  exactly 32 bits unsigned  uint_least32_t  at least 32 bits unsigned  uint_fast32_t  fast 32 bits unsigned

int64_t  exactly 64 bits signed  int_least64_t  at least 64 bits signed  int_fast64_t  fast 64 bits signed 
uint64_t  exactly 64 bits unsigned  uint_least64_t  at least 64 bits unsigned  uint_fast64_t  fast 64 bits unsigned 
The ptr aliases are integral types guaranteed to be large enough to hold a pointer without losing bits:
Alias  Description 

intptr_t  signed integral type large enough to hold a pointer 
uintptr_t  unsigned integral type large enough to hold a pointer 
The max aliases are the largest integral types:
Alias  Description 

intmax_t  the largest signed integral type 
uintmax_t  the largest unsigned integral type 
Authors:
Walter Bright, http://www.digitalmars.com
License:
Public Domain
Source:
std/stdint.d