The
<stdint.h> header provides source-portable integer types of a specific size, smallest memory footprint with a minimum size, fastest access speed with a minimum size, largest integer size, and those capable of storing pointers.
The types
int8_t,
int16_t,
int32_t, and
int64_t provide a signed integer type of width 8, 16, 32, or 64 bits, respectively. The types
uint8_t,
uint16_t,
uint32_t, and
uint64_t provide an unsigned integer type of width 8, 16, 32, or 64 bits, respectively. These integer types should be used when a specific size is required.
The types
int_fast8_t,
int_fast16_t,
int_fast32_t, and
int_fast64_t provide the fastest signed integer type with a width of at least 8, 16, 32, or 64 bits, respectively. The types
uint_fast8_t,
uint_fast16_t,
uint_fast32_t, and
uint_fast64_t provide the fastest unsigned integer type with a width of at least 8, 16, 32, or 64 bits, respectively. These types should be used when access speed is paramount, and when a specific size is not required.
The types
int_least8_t,
int_least16_t,
int_least32_t, and
int_least64_t provide the smallest memory footprint signed integer type with a width of at least 8, 16, 32, or 64 bits, respectively. The types
uint_least8_t,
uint_least16_t,
uint_least32_t, and
uint_least64_t provide the smallest memory footprint unsigned integer type with a width of at least 8, 16, 32, or 64 bits, respectively. These types should be used when memory storage is of concern, and when a specific size is not required.
The type
intmax_t provides a signed integer type large enough to hold any other signed integer. The type
uintmax_t provides an unsigned integer type large enough to hold any other unsigned integer. These types are generally the largest signed and unsigned integer types available on a specific architecture.
The type
intptr_t provides a signed integer type with the ability to hold a pointer to
void, that can later be converted back to a pointer to
void.
The type
uintptr_t provides an unsigned integer type with the ability to hold a pointer to
void, that can later be converted back to a pointer to
void.