Fixed width integer types (since C99)

Types

For each of the following typedef names marked (optional), an implementation defines it if and only if the implementation provides a corresponding type.

Defined in header `<stdint.h>`
int8_tint16_tint32_tint64_tintN_t (optional)(optional)(optional)(optional)(optional)	signed integer type with width of exactly N (typically 8, 16, 32 or 64) bits and no padding bits (typedef) [edit]
int_fast8_tint_fast16_tint_fast32_tint_fast64_tint_fastN_t (optional)	fastest signed integer type with width of at least N (typically 8, 16, 32 or 64) bits (typedef) [edit]
int_least8_tint_least16_tint_least32_tint_least64_tint_leastN_t (optional)	smallest signed integer type with width of at least N (typically 8, 16, 32 or 64) bits (if `intN_t` is defined, `int_leastN_t` designates the same type) (typedef) [edit]
intmax_t	maximum-width signed integer type other than a bit-precise integer type(since C23) (typedef) [edit]
intptr_t (optional)	signed integer type other than a bit-precise integer type(since C23) capable of holding a pointer to `void` (typedef) [edit]
uint8_tuint16_tuint32_tuint64_tuintN_t (optional)(optional)(optional)(optional)(optional)	unsigned integer type with width of exactly N (typically 8, 16, 32 or 64) bits and no padding bits (typedef) [edit]
uint_fast8_tuint_fast16_tuint_fast32_tuint_fast64_tuint_fastN_t (optional)	fastest unsigned integer type with width of at least N (typically 8, 16, 32 or 64) bits (typedef) [edit]
uint_least8_tuint_least16_tuint_least32_tuint_least64_tuint_leastN_t (optional)	smallest unsigned integer type with width of at least N (typically 8, 16, 32 or 64) bits (if `uintN_t` is defined, `uint_leastN_t` designates the same type) (typedef) [edit]
uintmax_t	maximum-width unsigned integer type other than a bit-precise integer type(since C23) (typedef) [edit]
uintptr_t (optional)	unsigned integer type other than a bit-precise integer type(since C23) capable of holding a pointer to `void` (typedef) [edit]

Macro constants

For each of the following macros marked (conditionally present), an implementation defines it if and only if the implementation defines the corresponding typedef name.

Defined in header `<stdint.h>`
Signed integers : bit width
INTN_WIDTH (C23)(conditionally present)	bit width of `intN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INT_FASTN_WIDTH (C23)(conditionally present)	bit width of `int_fastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INT_LEASTN_WIDTH (C23)(conditionally present)	bit width of `int_leastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INTMAX_WIDTH (C23)	bit width of `intmax_t` (macro constant) [edit]
INTPTR_WIDTH (C23)(conditionally present)	bit width of `intptr_t` (macro constant) [edit]
Signed integers : minimum value
INTN_MIN (conditionally present)	minimum value of `intN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INT_FASTN_MIN (conditionally present)	minimum value of `int_fastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INT_LEASTN_MIN (conditionally present)	minimum value of `int_leastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INTMAX_MIN	minimum value of `intmax_t` (macro constant) [edit]
INTPTR_MIN (conditionally present)	minimum value of `intptr_t` (macro constant) [edit]
Signed integers : maximum value
INTN_MAX (conditionally present)	maximum value of `intN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INT_FASTN_MAX (conditionally present)	maximum value of `int_fastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INT_LEASTN_MAX (conditionally present)	maximum value of `int_leastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
INTMAX_MAX	maximum value of `intmax_t` (macro constant) [edit]
INTPTR_MAX (conditionally present)	maximum value of `intptr_t` (macro constant) [edit]
Unsigned integers : bit width
UINTN_WIDTH (C23)(conditionally present)	bit width of `uintN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
UINT_FASTN_WIDTH (C23)(conditionally present)	bit width of `uint_fastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
UINT_LEASTN_WIDTH (C23)(conditionally present)	bit width of `uint_leastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
UINTMAX_WIDTH (C23)	bit width of `uintmax_t` (macro constant) [edit]
UINTPTR_WIDTH (C23)(conditionally present)	bit width of `uintptr_t` (macro constant) [edit]
Unsigned integers : maximum value
UINTN_MAX (conditionally present)	maximum value of `uintN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
UINT_FASTN_MAX (conditionally present)	maximum value of `uint_fastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
UINT_LEASTN_MAX (conditionally present)	maximum value of `uint_leastN_t` (N is typically 8, 16, 32 or 64) (macro constant) [edit]
UINTMAX_MAX	maximum value of `uintmax_t` (macro constant) [edit]
UINTPTR_MAX (conditionally present)	maximum value of `uintptr_t` (macro constant) [edit]

Function macros

For each of the following macros marked (conditionally present), an implementation defines it if and only if the implementation defines the corresponding typedef name.

INTN_C (conditionally present)	expands to an integer constant expression of type `int_leastN_t`, its value is specified by the argument (function macro) [edit]
	expands to an integer constant expression of type `intmax_t`, its value is specified by the argument (function macro) [edit]
UINTN_C (conditionally present)	expands to an integer constant expression of type `uint_leastN_t`, its value is specified by the argument (function macro) [edit]
	expands to an integer constant expression of type `uintmax_t`, its value is specified by the argument (function macro) [edit]

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

Format macro constants

Format constants for the fprintf family of functions

Each of the PRI macros listed here is defined if and only if the implementation defines the corresponding typedef name.

Equivalent for `int` or `unsigned int`	Description	Macros for data types
Equivalent for `int` or `unsigned int`	Description	`[u]intx_t`	`[u]int_leastx_t`	`[u]int_fastx_t`	`[u]intmax_t`	`[u]intptr_t`
`d`	output of a signed decimal integer value	PRIdx	PRIdLEASTx	PRIdFASTx	PRIdMAX	PRIdPTR
`i`	output of a signed decimal integer value	PRIix	PRIiLEASTx	PRIiFASTx	PRIiMAX	PRIiPTR
`u`	output of an unsigned decimal integer value	PRIux	PRIuLEASTx	PRIuFASTx	PRIuMAX	PRIuPTR
`o`	output of an unsigned octal integer value	PRIox	PRIoLEASTx	PRIoFASTx	PRIoMAX	PRIoPTR
`x`	output of an unsigned lowercase hexadecimal integer value	PRIxx	PRIxLEASTx	PRIxFASTx	PRIxMAX	PRIxPTR
`X`	output of an unsigned uppercase hexadecimal integer value	PRIXx	PRIXLEASTx	PRIXFASTx	PRIXMAX	PRIXPTR

Format constants for the fscanf family of functions

Each of the SCN macros listed in here is defined if and only if the implementation defines the corresponding typedef name and has a suitable fscanf length modifier for the type.

Equivalent for `int` or `unsigned int`	Description	Macros for data types
Equivalent for `int` or `unsigned int`	Description	`[u]intx_t`	`[u]int_leastx_t`	`[u]int_fastx_t`	`[u]intmax_t`	`[u]intptr_t`
`d`	input of a signed decimal integer value	SCNdx	SCNdLEASTx	SCNdFASTx	SCNdMAX	SCNdPTR
`i`	input of a signed integer value (base is determined by the first characters parsed)	SCNix	SCNiLEASTx	SCNiFASTx	SCNiMAX	SCNiPTR
`u`	input of an unsigned decimal integer value	SCNux	SCNuLEASTx	SCNuFASTx	SCNuMAX	SCNuPTR
`o`	input of an unsigned octal integer value	SCNox	SCNoLEASTx	SCNoFASTx	SCNoMAX	SCNoPTR
`x`	input of an unsigned hexadecimal integer value	SCNxx	SCNxLEASTx	SCNxFASTx	SCNxMAX	SCNxPTR

Example

See also C++ compatibility note regarding spaces before format macros used in this example.

#include <inttypes.h>
#include <stdio.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);
}

Possible output:

8
lld
-9223372036854775808
+9223372036854775807
+7

References

C23 standard (ISO/IEC 9899:2024):

7.8.1 Macros for format specifiers (p: TBD)

7.18 Integer types <stdint.h> (p: TBD)

C17 standard (ISO/IEC 9899:2018):

7.8.1 Macros for format specifiers (p: 158-159)

7.18 Integer types <stdint.h> (p: 212-216)

C11 standard (ISO/IEC 9899:2011):

7.8.1 Macros for format specifiers (p: 217-218)

7.18 Integer types <stdint.h> (p: 289-295)

C99 standard (ISO/IEC 9899:1999):

7.8.1 Macros for format specifiers (p: 198-199)

7.18 Integer types <stdint.h> (p: 255-261)

Fixed width integer types (since C99)

Types

Macro constants

Signed integers : bit width

Signed integers : minimum value

Signed integers : maximum value

Unsigned integers : bit width