Fixed width integer types (since C99)

 

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Atomic operations (C11)

Thread support (C11)

Technical Specifications

 

Type support

size_t

ptrdiff_t

NULL

max_align_t (since C11)

offsetof

Numeric limits

 

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_MININT16_MININT32_MININT64_MIN	minimum value of an object of type int8_t, int16_t, int32_t, int64_t (macro constant)
INT_FAST8_MININT_FAST16_MININT_FAST32_MININT_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_MININT_LEAST16_MININT_LEAST32_MININT_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_MAXINT16_MAXINT32_MAXINT64_MAX	maximum value of an object of type int8_t, int16_t, int32_t, int64_t (macro constant)
INT_FAST8_MAXINT_FAST16_MAXINT_FAST32_MAXINT_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_MAXINT_LEAST16_MAXINT_LEAST32_MAXINT_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_MAXUINT16_MAXUINT32_MAXUINT64_MAX	maximum value of an object of type uint8_t, uint16_t, uint32_t, uint64_t (macro constant)
UINT_FAST8_MAXUINT_FAST16_MAXUINT_FAST32_MAXUINT_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_MAXUINT_LEAST16_MAXUINT_LEAST32_MAXUINT_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_CINT16_CINT32_CINT64_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_CUINT16_CUINT32_CUINT64_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

Equivalent for int or unsigned int	Description	Macros for data types
		[u]intx_t	[u]int_leastx_t	[u]int_fastx_t	[u]intmax_t	[u]intptr_t
		x = 8, 16, 32 or 64
d	output of a signed decimal integer value	PRIdx	PRIdLEASTx	PRIdFASTx	PRIdMAX	PRIdPTR
i		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

Equivalent for int or unsigned int	Description	Macros for data types
		[u]intx_t	[u]int_leastx_t	[u]int_fastx_t	[u]intmax_t	[u]intptr_t
		x = 8, 16, 32 or 64
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

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);
}

Possible output:

8
lld
-9223372036854775808
+9223372036854775807
+7

See also

• Arithmetic types

C++ documentation for Fixed width integer types