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)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Dynamic memory management Program utilities Coroutine support (C++20) Variadic functions is_constant_evaluated (C++20) is_within_lifetime (C++26) initializer_list (C++11) source_location (C++20) 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 Date and time Function objects Formatting library (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) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17) to_chars_result (C++17) from_chars_result (C++17)

 

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

Defined in header <cstdint>
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 (optional)	signed integer type capable of holding a pointer to void (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 (optional)	unsigned integer type capable of holding a pointer to void (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, std::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 <cstdint>
Signed integers : minimum value
INT8_MININT16_MININT32_MININT64_MIN (optional)	minimum value of std::int8_t, std::int16_t, std::int32_t and std::int64_t respectively (macro constant)
INT_FAST8_MININT_FAST16_MININT_FAST32_MININT_FAST64_MIN	minimum value of std::int_fast8_t, std::int_fast16_t, std::int_fast32_t and std::int_fast64_t respectively (macro constant)
INT_LEAST8_MININT_LEAST16_MININT_LEAST32_MININT_LEAST64_MIN	minimum value of std::int_least8_t, std::int_least16_t, std::int_least32_t and std::int_least64_t respectively (macro constant)
INTPTR_MIN (optional)	minimum value of std::intptr_t (macro constant)
INTMAX_MIN	minimum value of std::intmax_t (macro constant)
Signed integers : maximum value
INT8_MAXINT16_MAXINT32_MAXINT64_MAX (optional)	maximum value of std::int8_t, std::int16_t, std::int32_t and std::int64_t respectively (macro constant)
INT_FAST8_MAXINT_FAST16_MAXINT_FAST32_MAXINT_FAST64_MAX	maximum value of std::int_fast8_t, std::int_fast16_t, std::int_fast32_t and std::int_fast64_t respectively (macro constant)
INT_LEAST8_MAXINT_LEAST16_MAXINT_LEAST32_MAXINT_LEAST64_MAX	maximum value of std::int_least8_t, std::int_least16_t, std::int_least32_t and std::int_least64_t respectively (macro constant)
INTPTR_MAX (optional)	maximum value of std::intptr_t (macro constant)
INTMAX_MAX	maximum value of std::intmax_t (macro constant)
Unsigned integers : maximum value
UINT8_MAXUINT16_MAXUINT32_MAXUINT64_MAX (optional)	maximum value of std::uint8_t, std::uint16_t, std::uint32_t and std::uint64_t respectively (macro constant)
UINT_FAST8_MAXUINT_FAST16_MAXUINT_FAST32_MAXUINT_FAST64_MAX	maximum value of std::uint_fast8_t, std::uint_fast16_t, std::uint_fast32_t and std::uint_fast64_t respectively (macro constant)
UINT_LEAST8_MAXUINT_LEAST16_MAXUINT_LEAST32_MAXUINT_LEAST64_MAX	maximum value of std::uint_least8_t, std::uint_least16_t, std::uint_least32_t and std::uint_least64_t respectively (macro constant)
UINTPTR_MAX (optional)	maximum value of std::uintptr_t (macro constant)
UINTMAX_MAX	maximum value of std::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 whose type is the promoted type of std::int_least8_t, std::int_least16_t, std::int_least32_t and std::int_least64_t respectively (function macro)
INTMAX_C	expands to an integer constant expression having the value specified by its argument and the type std::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 std::uint_least8_t, std::uint_least16_t, std::uint_least32_t and std::uint_least64_t respectively (function macro)
UINTMAX_C	expands to an integer constant expression having the value specified by its argument and the type std::uintmax_t (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