Which is a type of long

[See also type for type system overview and the list of type-related utilities that are provided by the C++ library]

Contents

• 1 Void type
• 2 std::nullptr_t
• 3 Data models
• 4 Signed and unsigned integer types
  • 4.1 Modifiers
  • 4.2 Properties
• 5 Boolean type
• 6 Character types
• 7 Floating-point types
  • 7.1 Properties
• 8 Range of values
• 9 Notes
• 10 Keywords
• 11 Defect reports
• 12 See also

[edit] Void type

void - type with an empty set of values. It is an incomplete type that cannot be completed [consequently, objects of type void are disallowed]. There are no arrays of void, nor references to void. However, pointers to void and functions returning type void [procedures in other languages] are permitted.

[edit] std::nullptr_t

typedef decltype[nullptr] nullptr_t;		[since C++11]

std::nullptr_t is the type of the null pointer literal, nullptr. It is a distinct type that is not itself a pointer type or a pointer to member type. Its values are null pointer constant [see NULL], and may be implicitly converted to any pointer and pointer to member type.

sizeof[std::nullptr_t] is equal to sizeof[void *].

[edit] Data models

The choices made by each implementation about the sizes of the fundamental types are collectively known as data model. Four data models found wide acceptance:

32 bit systems:

• LP32 or 2/4/4 [int is 16-bit, long and pointer are 32-bit]

• Win16 API

• ILP32 or 4/4/4 [int, long, and pointer are 32-bit];

• Win32 API
• Unix and Unix-like systems [Linux, macOS]

64 bit systems:

• LLP64 or 4/4/8 [int and long are 32-bit, pointer is 64-bit]

• Win64 API

• LP64 or 4/8/8 [int is 32-bit, long and pointer are 64-bit]

• Unix and Unix-like systems [Linux, macOS]

Other models are very rare. For example, ILP64 [8/8/8: int, long, and pointer are 64-bit] only appeared in some early 64-bit Unix systems [e.g. UNICOS on Cray].

[edit] Signed and unsigned integer types

int - basic integer type. The keyword int may be omitted if any of the modifiers listed below are used. If no length modifiers are present, it's guaranteed to have a width of at least 16 bits. However, on 32/64 bit systems it is almost exclusively guaranteed to have width of at least 32 bits [see below].

[edit] Modifiers

Modifies the basic integer type. Can be mixed in any order. Only one of each group can be present in type name.

Signedness

signed - target type will have signed representation [this is the default if omitted] unsigned - target type will have unsigned representation

Size

short - target type will be optimized for space and will have width of at least 16 bits. long - target type will have width of at least 32 bits.

long long - target type will have width of at least 64 bits.

[since C++11]

Note: as with all type specifiers, any order is permitted: unsigned long long int and long int unsigned long name the same type.

[edit] Properties

The following table summarizes all available integer types and their properties in various common data models:

Type specifier Equivalent type Width in bits by data model C++ standard LP32 ILP32 LLP64 LP64

signed char	signed char	at least 8	8	8	8	8
unsigned char	unsigned char
short	short int	at least 16	16	16	16	16
short int
signed short
signed short int
unsigned short	unsigned short int
unsigned short int
int	int	at least 16	16	32	32	32
signed
signed int
unsigned	unsigned int
unsigned int
long	long int	at least 32	32	32	32	64
long int
signed long
signed long int
unsigned long	unsigned long int
unsigned long int
long long	long long int [C++11]	at least 64	64	64	64	64
long long int
signed long long
signed long long int
unsigned long long	unsigned long long int [C++11]
unsigned long long int

Note: integer arithmetic is defined differently for the signed and unsigned integer types. See arithmetic operators, in particular integer overflows.

std::size_t is the unsigned integer type of the result of the sizeof operator as well as the sizeof... operator and the alignof operator [since C++11].

[edit] Boolean type

bool - type, capable of holding one of the two values: true or false. The value of sizeof[bool] is implementation defined and might differ from 1.

[edit] Character types

signed char - type for signed character representation. unsigned char - type for unsigned character representation. Also used to inspect object representations [raw memory]. char - type for character representation which can be most efficiently processed on the target system [has the same representation and alignment as either signed char or unsigned char, but is always a distinct type]. Multibyte characters strings use this type to represent code units. For every value of type unsigned char in range [0, 255], converting the value to char and then back to unsigned char produces the original value. [since C++11] The signedness of char depends on the compiler and the target platform: the defaults for ARM and PowerPC are typically unsigned, the defaults for x86 and x64 are typically signed. wchar_t - type for wide character representation [see wide strings]. It has the same size, signedness, and alignment as one of the integer types, but is a distinct type. In practice, it is 32 bits and holds UTF-32 on Linux and many other non-Windows systems, but 16 bits and holds UTF-16 code units on Windows. The standard used to require wchar_t to be large enough to represent any supported character code point. However, such requirement cannot be fulfilled on Windows, and thus it is considered as a defect and removed.

char16_t - type for UTF-16 character representation, required to be large enough to represent any UTF-16 code unit [16 bits]. It has the same size, signedness, and alignment as std::uint_least16_t, but is a distinct type. char32_t - type for UTF-32 character representation, required to be large enough to represent any UTF-32 code unit [32 bits]. It has the same size, signedness, and alignment as std::uint_least32_t, but is a distinct type.

[since C++11]

char8_t - type for UTF-8 character representation, required to be large enough to represent any UTF-8 code unit [8 bits]. It has the same size, signedness, and alignment as unsigned char [and therefore, the same size and alignment as char and signed char], but is a distinct type.

[since C++20]

Besides the minimal bit counts, the C++ Standard guarantees that

1 == sizeof[char]