Fixed width integer types (since C++11)

Types

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

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.

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.

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

Format macro constants

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.

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.

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

#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);
}

8
lld
-9223372036854775808
+9223372036854775807
+7

Defect reports

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

References

See also

• Fundamental types