Fixed width integer types (since C99)

 

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Technical Specifications

 

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Types

Defined in header <stdint.h>
int8_t int16_t int32_t int64_t	signed integer type with width of exactly 8, 16, 32 and 64 bits respectively with no padding bits and using 2's complement for negative values (provided only if the implementation directly supports the type)
int_fast8_t int_fast16_t int_fast32_t int_fast64_t	fastest signed integer type with width of at least 8, 16, 32 and 64 bits respectively
int_least8_t int_least16_t int_least32_t int_least64_t	smallest signed integer type with width of at least 8, 16, 32 and 64 bits respectively
intmax_t	maximum width integer type
intptr_t	integer type capable of holding a pointer
uint8_t uint16_t uint32_t uint64_t	unsigned integer type with width of exactly 8, 16, 32 and 64 bits respectively (provided only if the implementation directly supports the type)
uint_fast8_t uint_fast16_t uint_fast32_t uint_fast64_t	fastest unsigned integer type with width of at least 8, 16, 32 and 64 bits respectively
uint_least8_t uint_least16_t uint_least32_t uint_least64_t	smallest unsigned integer type with width of at least 8, 16, 32 and 64 bits respectively
uintmax_t	maximum width unsigned integer type
uintptr_t	unsigned integer type capable of holding a pointer

Macro constants

Defined in header <stdint.h>
Signed integers : minimum value
INT8_MIN INT16_MIN INT32_MIN INT64_MIN	minimum value of an object of type int8_t, int16_t, int32_t, int64_t (macro constant)
INT_FAST8_MIN INT_FAST16_MIN INT_FAST32_MIN INT_FAST64_MIN	minimum value of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t (macro constant)
INT_LEAST8_MIN INT_LEAST16_MIN INT_LEAST32_MIN INT_LEAST64_MIN	minimum value of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t (macro constant)
INTPTR_MIN	minimum value of an object of type intptr_t (macro constant)
INTMAX_MIN	minimum value of an object of type intmax_t (macro constant)
Signed integers : maximum value
INT8_MAX INT16_MAX INT32_MAX INT64_MAX	maximum value of an object of type int8_t, int16_t, int32_t, int64_t (macro constant)
INT_FAST8_MAX INT_FAST16_MAX INT_FAST32_MAX INT_FAST64_MAX	maximum value of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t (macro constant)
INT_LEAST8_MAX INT_LEAST16_MAX INT_LEAST32_MAX INT_LEAST64_MAX	maximum value of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t (macro constant)
INTPTR_MAX	maximum value of an object of type intptr_t (macro constant)
INTMAX_MAX	maximum value of an object of type intmax_t (macro constant)
Unsigned integers : maximum value
UINT8_MAX UINT16_MAX UINT32_MAX UINT64_MAX	maximum value of an object of type uint8_t, uint16_t, uint32_t, uint64_t (macro constant)
UINT_FAST8_MAX UINT_FAST16_MAX UINT_FAST32_MAX UINT_FAST64_MAX	maximum value of an object of type uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t (macro constant)
UINT_LEAST8_MAX UINT_LEAST16_MAX UINT_LEAST32_MAX UINT_LEAST64_MAX	maximum value of an object of type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t (macro constant)
UINTPTR_MAX	maximum value of an object of type uintptr_t (macro constant)
UINTMAX_MAX	maximum value of an object of type uintmax_t (macro constant)

Function macros for minimum-width integer constants

INT8_C INT16_C INT32_C INT64_C	expands to an integer constant expression having the value specified by its argument and the type int_least8_t, int_least16_t, int_least32_t, int_least64_t respectively (function macro)
INTMAX_C	expands to an integer constant expression having the value specified by its argument and the type intmax_t (function macro)
UINT8_C UINT16_C UINT32_C UINT64_C	expands to an integer constant expression having the value specified by its argument and the type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t respectively (function macro)
UINTMAX_C	expands to an integer constant expression having the value specified by its argument and the type uintmax_t (function macro)

#include <stdint.h>
UINT64_C(0x123) // might expand to 0x123ULL or 0x123UL

Format macro constants

Defined in header <inttypes.h>
Format constants for the fprintf family of functions
PRId8 PRId16 PRId32 PRId64 PRIdLEAST8 PRIdLEAST16 PRIdLEAST32 PRIdLEAST64 PRIdFAST8 PRIdFAST16 PRIdFAST32 PRIdFAST64 PRIdMAX PRIdPTR	format conversion specifier to output a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %d for int (macro constant)
PRIi8 PRIi16 PRIi32 PRIi64 PRIiLEAST8 PRIiLEAST16 PRIiLEAST32 PRIiLEAST64 PRIiFAST8 PRIiFAST16 PRIiFAST32 PRIiFAST64 PRIiMAX PRIiPTR	format conversion specifier to output a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %i for int (macro constant)
PRIu8 PRIu16 PRIu32 PRIu64 PRIuLEAST8 PRIuLEAST16 PRIuLEAST32 PRIuLEAST64 PRIuFAST8 PRIuFAST16 PRIuFAST32 PRIuFAST64 PRIuMAX PRIuPTR	format conversion specifier to output an unsigned decimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %u for unsigned int (macro constant)
PRIo8 PRIo16 PRIo32 PRIo64 PRIoLEAST8 PRIoLEAST16 PRIoLEAST32 PRIoLEAST64 PRIoFAST8 PRIoFAST16 PRIoFAST32 PRIoFAST64 PRIoMAX PRIoPTR	format conversion specifier to output an unsigned octal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %o for unsigned int (macro constant)
PRIx8 PRIx16 PRIx32 PRIx64 PRIxLEAST8 PRIxLEAST16 PRIxLEAST32 PRIxLEAST64 PRIxFAST8 PRIxFAST16 PRIxFAST32 PRIxFAST64 PRIxMAX PRIxPTR	format conversion specifier to output an unsigned hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %x for unsigned int (macro constant)
PRIX8 PRIX16 PRIX32 PRIX64 PRIXLEAST8 PRIXLEAST16 PRIXLEAST32 PRIXLEAST64 PRIXFAST8 PRIXFAST16 PRIXFAST32 PRIXFAST64 PRIXMAX PRIXPTR	format conversion specifier to output an unsigned uppercase hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %X for unsigned int (macro constant)
Format constants for the fscanf family of functions
SCNd8 SCNd16 SCNd32 SCNd64 SCNdLEAST8 SCNdLEAST16 SCNdLEAST32 SCNdLEAST64 SCNdFAST8 SCNdFAST16 SCNdFAST32 SCNdFAST64 SCNdMAX SCNdPTR	format conversion specifier to input a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %d for int (macro constant)
SCNi8 SCNi16 SCNi32 SCNi64 SCNiLEAST8 SCNiLEAST16 SCNiLEAST32 SCNiLEAST64 SCNiFAST8 SCNiFAST16 SCNiFAST32 SCNiFAST64 SCNiMAX SCNiPTR	format conversion specifier to input a signed decimal/octal/hexadecimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to %i for int (macro constant)
SCNu8 SCNu16 SCNu32 SCNu64 SCNuLEAST8 SCNuLEAST16 SCNuLEAST32 SCNuLEAST64 SCNuFAST8 SCNuFAST16 SCNuFAST32 SCNuFAST64 SCNuMAX SCNuPTR	format conversion specifier to input an unsigned decimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %u for unsigned int (macro constant)
SCNo8 SCNo16 SCNo32 SCNo64 SCNoLEAST8 SCNoLEAST16 SCNoLEAST32 SCNoLEAST64 SCNoFAST8 SCNoFAST16 SCNoFAST32 SCNoFAST64 SCNoMAX SCNoPTR	format conversion specifier to input an unsigned octal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %o for unsigned int (macro constant)
SCNx8 SCNx16 SCNx32 SCNx64 SCNxLEAST8 SCNxLEAST16 SCNxLEAST32 SCNxLEAST64 SCNxFAST8 SCNxFAST16 SCNxFAST32 SCNxFAST64 SCNxMAX SCNxPTR	format conversion specifier to input an unsigned hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %x for unsigned int (macro constant)
SCNX8 SCNX16 SCNX32 SCNX64 SCNXLEAST8 SCNXLEAST16 SCNXLEAST32 SCNXLEAST64 SCNXFAST8 SCNXFAST16 SCNXFAST32 SCNXFAST64 SCNXMAX SCNXPTR	format conversion specifier to input an unsigned uppercase hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to %X for unsigned int (macro constant)

Example

Run this code

#include <stdio.h>
#include <inttypes.h>
 
int main(void)
{
    printf("%zu\n", sizeof(int64_t));
    printf("%s\n", PRId64);
    printf("%+"PRId64"\n", INT64_MIN);
    printf("%+"PRId64"\n", INT64_MAX);
 
    int64_t n = 7;
    printf("%+"PRId64"\n", n);
 
    return 0;
}

Possible output:

8
ld
-9223372036854775808
+9223372036854775807
+7

See also

• Arithmetic types
• C++ type system overview
• Type support (basic types, RTTI, type traits)