Fixed width integer types (since C99)

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C
 
Type support
(C11)
Numeric limits
Fixed width integer types (C99)
 

Types

Defined in header <stdint.h>
int8_tint16_tint32_tint64_t
(optional)
 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 if and only if the implementation directly supports the type)
(typedef)
int_fast8_tint_fast16_tint_fast32_tint_fast64_t
 fastest signed integer type with width of at least 8, 16, 32 and 64 bits respectively
(typedef)
int_least8_tint_least16_tint_least32_tint_least64_t
 smallest signed integer type with width of at least 8, 16, 32 and 64 bits respectively
(typedef)
intmax_t
 maximum-width signed integer type
(typedef)
intptr_t
 signed integer type capable of holding a pointer
(This type need not be available)
(typedef)
uint8_tuint16_tuint32_tuint64_t
(optional)
 unsigned integer type with width of exactly 8, 16, 32 and 64 bits respectively
(provided if and only if the implementation directly supports the type)
(typedef)
uint_fast8_tuint_fast16_tuint_fast32_tuint_fast64_t
 fastest unsigned integer type with width of at least 8, 16, 32 and 64 bits respectively
(typedef)
uint_least8_tuint_least16_tuint_least32_tuint_least64_t
 smallest unsigned integer type with width of at least 8, 16, 32 and 64 bits respectively
(typedef)
uintmax_t
 maximum-width unsigned integer type
(typedef)
uintptr_t
 unsigned integer type capable of holding a pointer
(This type need not be available)
(typedef)

The implementation may define typedef names intN_t, int_fastN_t, int_leastN_t, uintN_t, uint_fastN_t, and uint_leastN_t when N is not 8, 16, 32 or 64. Typedef names of the form intN_t may only be defined if the implementation supports an integer type of that width with no padding. Thus, uint24_t denotes an unsigned integer type with a width of exactly 24 bits.

Each of the macros listed in below is defined if and only if the implementation defines the corresponding typedef name. The macros INTN_C and UINTN_C correspond to the typedef names int_leastN_t and uint_leastN_t, respectively.

Macro constants

Defined in header <stdint.h>
Signed integers : width
INT8_WIDTHINT16_WIDTHINT32_WIDTHINT64_WIDTH
(C23)(optional)
 bit width of an object of type int8_t, int16_t, int32_t, int64_t (exactly 8, 16, 32, 64)
(macro constant)
INT_FAST8_WIDTHINT_FAST16_WIDTHINT_FAST32_WIDTHINT_FAST64_WIDTH
(C23)
 bit width of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t
(macro constant)
INT_LEAST8_WIDTHINT_LEAST16_WIDTHINT_LEAST32_WIDTHINT_LEAST64_WIDTH
(C23)
 bit width of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t
(macro constant)
INTPTR_WIDTH
(C23)(optional)
 bit width of an object of type intptr_t
(macro constant)
INTMAX_WIDTH
(C23)
 bit width of an object of type intmax_t
(macro constant)
Signed integers : minimum value
INT8_MININT16_MININT32_MININT64_MIN
(optional)
 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
(optional)
 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
(optional)
 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
(optional)
 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 : width
UINT8_WIDTHUINT16_WIDTHUINT32_WIDTHUINT64_WIDTH
(C23)(optional)
 bit width of an object of type uint8_t, uint16_t, uint32_t, uint64_t (exactly 8, 16, 32, 64)
(macro constant)
UINT_FAST8_WIDTHUINT_FAST16_WIDTHUINT_FAST32_WIDTHUINT_FAST64_WIDTH
(C23)
 bit width of an object of type uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t
(macro constant)
UINT_LEAST8_WIDTHUINT_LEAST16_WIDTHUINT_LEAST32_WIDTHUINT_LEAST64_WIDTH
(C23)
 bit width of an object of type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t
(macro constant)
UINTPTR_WIDTH
(C23)(optional)
 bit width of an object of type uintptr_t
(macro constant)
UINTMAX_WIDTH
(C23)
 bit width of an object of type uintmax_t
(macro constant)
Unsigned integers : maximum value
UINT8_MAXUINT16_MAXUINT32_MAXUINT64_MAX
(optional)
 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
(optional)
 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

Defined in header <stdint.h>
INT8_CINT16_CINT32_CINT64_C
 expands to an integer constant expression having the value specified by its argument and whose type is the promoted type of 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 whose type is the promoted type of 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

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




[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 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




[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

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

References

  • 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)

See also

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