Fixed width integer types (since C++11)

 

C++

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Program utilities Variadic functions initializer_list (C++11) is_constant_evaluated (C++20) is_within_lifetime (C++26) source_location (C++20) Coroutine support (C++20) Contract support (C++26) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Function objects Bit manipulation (C++20) bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23)

 

Type support

Basic types
Fixed width integer types (C++11)
Fixed width floating-point types (C++23)
ptrdiff_t size_t max_align_t (C++11)     byte (C++17)	nullptr_t (C++11) offsetof NULL
Numeric limits
numeric_limits
C numeric limits interface
Runtime type information
type_info type_index (C++11)	bad_typeid bad_cast

 

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 <cstdint>
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)
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)
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 std::intN_t is defined, std::int_leastN_t designates the same type) (typedef)
intmax_t	maximum-width signed integer type (typedef)
intptr_t (optional)	signed integer type capable of holding a pointer to void (typedef)
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)
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)
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 std::uintN_t is defined, std::uint_leastN_t designates the same type) (typedef)
uintmax_t	maximum-width unsigned integer type (typedef)
uintptr_t (optional)	unsigned integer type capable of holding a pointer to void (typedef)

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 <cstdint>
Signed integers : bit width
INTN_WIDTH (C++26)(conditionally present)	bit width of std::intN_t (N is typically 8, 16, 32 or 64) (macro constant)
INT_FASTN_WIDTH (C++26)(conditionally present)	bit width of std::int_fastN_t (N is typically 8, 16, 32 or 64) (macro constant)
INT_LEASTN_WIDTH (C++26)(conditionally present)	bit width of std::int_leastN_t (N is typically 8, 16, 32 or 64) (macro constant)
INTMAX_WIDTH (C++26)	bit width of std::intmax_t (macro constant)
INTPTR_WIDTH (C++26)(conditionally present)	bit width of std::intptr_t (macro constant)
Signed integers : minimum value
INTN_MIN (conditionally present)	minimum value of std::intN_t (N is typically 8, 16, 32 or 64) (macro constant)
INT_FASTN_MIN (conditionally present)	minimum value of std::int_fastN_t (N is typically 8, 16, 32 or 64) (macro constant)
INT_LEASTN_MIN (conditionally present)	minimum value of std::int_leastN_t (N is typically 8, 16, 32 or 64) (macro constant)
INTMAX_MIN	minimum value of std::intmax_t (macro constant)
INTPTR_MIN (conditionally present)	minimum value of std::intptr_t (macro constant)
Signed integers : maximum value
INTN_MAX (conditionally present)	maximum value of std::intN_t (N is typically 8, 16, 32 or 64) (macro constant)
INT_FASTN_MAX (conditionally present)	maximum value of std::int_fastN_t (N is typically 8, 16, 32 or 64) (macro constant)
INT_LEASTN_MAX (conditionally present)	maximum value of std::int_leastN_t (N is typically 8, 16, 32 or 64) (macro constant)
INTMAX_MAX	maximum value of std::intmax_t (macro constant)
INTPTR_MAX (conditionally present)	maximum value of std::intptr_t (macro constant)
Unsigned integers : bit width
UINTN_WIDTH (C++26)(conditionally present)	bit width of std::uintN_t (N is typically 8, 16, 32 or 64) (macro constant)
UINT_FASTN_WIDTH (C++26)(conditionally present)	bit width of std::uint_fastN_t (N is typically 8, 16, 32 or 64) (macro constant)
UINT_LEASTN_WIDTH (C++26)(conditionally present)	bit width of std::uint_leastN_t (N is typically 8, 16, 32 or 64) (macro constant)
UINTMAX_WIDTH (C++26)	bit width of std::uintmax_t (macro constant)
UINTPTR_WIDTH (C++26)(conditionally present)	bit width of std::uintptr_t (macro constant)
Unsigned integers : maximum value
UINTN_MAX (conditionally present)	maximum value of std::uintN_t (N is typically 8, 16, 32 or 64) (macro constant)
UINT_FASTN_MAX (conditionally present)	maximum value of std::uint_fastN_t (N is typically 8, 16, 32 or 64) (macro constant)
UINT_LEASTN_MAX (conditionally present)	maximum value of std::uint_leastN_t (N is typically 8, 16, 32 or 64) (macro constant)
UINTMAX_MAX	maximum value of std::uintmax_t (macro constant)
UINTPTR_MAX (conditionally present)	maximum value of std::uintptr_t (macro constant)

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.

Defined in header <cstdint>
INTN_C (conditionally present)	expands to an integer constant expression of type std::int_leastN_t, its value is specified by the argument (function macro)
INTMAX_C	expands to an integer constant expression of type std::intmax_t, its value is specified by the argument (function macro)
UINTN_C (conditionally present)	expands to an integer constant expression of type std::uint_leastN_t, its value is specified by the argument (function macro)
UINTMAX_C	expands to an integer constant expression of type std::uintmax_t, its value is specified by the argument (function macro)

#include <cstdint>
UINT64_C(0x123) // expands to a literal of type uint_least64_t and value 0x123

Format macro constants

Defined in header <cinttypes>

Format constants for the std::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
		std::intx_t	std::int_leastx_t	std::int_fastx_t	std::intmax_t	std::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 std::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 std::fscanf length modifier for the type.

Equivalent for int or unsigned int	Description	Macros for data types
		std::intx_t	std::int_leastx_t	std::int_fastx_t	std::intmax_t	std::intptr_t
d	input of a signed decimal integer value	SCNdx	SCNdLEASTx	SCNdFASTx	SCNdMAX	SCNdPTR
i	input of a signed integer value	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

Notes

Because C++ interprets a character immediately following a string literal as a user-defined string literal, C code such as printf("%"PRId64"\n",n); is invalid C++ and requires a space before PRId64.

The C99 standard suggests that C++ implementations should not define the above limit, constant, or format macros unless the macros __STDC_LIMIT_MACROS, __STDC_CONSTANT_MACROS or __STDC_FORMAT_MACROS (respectively) are defined before including the relevant C header (stdint.h or inttypes.h). This recommendation was not adopted by any C++ standard and was removed in C11. However, some implementations (such as glibc 2.17) try to apply this rule, and it may be necessary to define the __STDC macros; C++ compilers may try to work around this by automatically defining them in some circumstances.

std::int8_t may be signed char and std::uint8_t may be unsigned char, but neither can be char regardless of its signedness (because char is not considered a "signed integer type" or "unsigned integer type").

Example

See also a note regarding spaces before format macros used in this example.

Run this code

#include <cinttypes>
#include <cstdio>

int main()
{
    std::printf("%zu\n", sizeof(std::int64_t));
    std::printf("%s\n", PRId64);
    std::printf("%+" PRId64 "\n", INT64_MIN);
    std::printf("%+" PRId64 "\n", INT64_MAX);
    
    std::int64_t n = 7;
    std::printf("%+" PRId64 "\n", n);
}

Possible output:

8
lld
-9223372036854775808
+9223372036854775807
+7

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2820	C++11	the requirements for optional typedef names and macros were inconsistent with C	made consistent

References

• C++23 standard (ISO/IEC 14882:2024):

• 17.4.1 Header <cstdint> synopsis [cstdint.syn]

• 31.13.2 Header <cinttypes> synopsis [cinttypes.syn]

• C++20 standard (ISO/IEC 14882:2020):

• 17.4 Integer types [cstdint]

• 29.12.2 Header <cinttypes> synopsis [cinttypes.syn]

• C++17 standard (ISO/IEC 14882:2017):

• 21.4 Integer types [cstdint]

• 30.11.2 Header <cinttypes> synopsis [cinttypes.syn]

• C++14 standard (ISO/IEC 14882:2014):

• 18.4 Integer types [cstdint]

• 27.9.2 C library files [c.files]

• C++11 standard (ISO/IEC 14882:2011):

• 18.4 Integer types [cstdint]

• 27.9.2 C library files [c.files]

See also

• Fundamental types

C documentation for Fixed width integer types