Fundamental types

来自cppreference.com
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C++语言
表达式
替代表示
字面量
布尔型 - 整型 - 浮点型
字符型 - 字符串 - nullptr (C++11)
用户定义 (C++11)
Utilities
属性 (C++11)
Types
typedef声明
类型别名声明 (C++11)
Casts
隐式类型转换 - 显示类型转换
static_cast - dynamic_cast
const_cast - reinterpret_cast
内存分配
类特有的函数属性
explicit (C++11)
static
静态成员函数
模板
杂项
 

(Also see the list of type-related utilities that are provided by C++.)

目录

[编辑] Boolean type

bool - type, capable of holding one of the two values: true or false.

[编辑] Character types

signed char - type for signed character representation.
unsigned char - type for unsigned character representation.
char - type for character representation which can be most efficiently processed on the target system (equivalent to either signed char or unsigned char).
wchar_t - type for wide character representation
char16_t - type for UTF-16 character representation (C++11起)
char32_t - type for UTF-32 character representation (C++11起)

[编辑] Integer types

int - basic integer type. Can be omitted if any of the modifiers are present. If no length modifiers are present, guaranteed to have 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).

[编辑] 修饰符

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

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 (C++11起)

[编辑] Properties

The following table summarizes all available integer types and their properties:

Type specifier Equivalent type Width in bits by data model
C++ standard LP32 ILP32 LLP64 LP64
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: the C++ Standard guarantees that 1 == sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long) <= sizeof(long long).

[编辑] Data models

32 bit systems:

  • LP32:
  • Win16 API
  • ILP32;
  • Win32 API
  • Unix and Unix-like systems (Linux, Mac OS X)

64 bit systems:

  • LLP64
  • Win64 API
  • LP64
  • Unix and Unix-like systems (Linux, Mac OS X)

[编辑] Floating point types

float - single precision floating point type. Usually IEEE-754 32 bit floating point type
double - double precision floating point type. Usually IEEE-754 64 bit floating point type
long double - extended precision floating point type. Does not necessarily map to types mandated by IEEE-754. Usually 80-bit x87 floating point type on x86 and x86-64 architectures.

[编辑] Range of values

The following table provides a reference for limits of common numeric representations. Note, that all popular data models (including all of ILP32, LP32, LP64, LLP64) use two's complement arithmetic. Also, the C++ Standard does not specify which arithmetic would be used, thus it guarantees only the limits of one's complement arithmetic.

Type Size in bits Format Value range
Approximate Exact
character 8 signed (one's complement) -127 to 127
signed (two's complement) -128 to 127
unsigned 0 to 255
integral 16 signed (one's complement) ± 3.27 · 104 -32767 to 32767
signed (two's complement) -32768 to 32767
unsigned 0 to 6.55 · 104 0 to 65535
32 signed (one's complement) ± 2.14 · 109 -2,147,483,647 to 2,147,483,647
signed (two's complement) -2,147,483,648 to 2,147,483,647
unsigned 0 to 4.29 · 109 0 to 4,294,967,295
64 signed (one's complement) ± 9.22 · 1018 -9,223,372,036,854,775,807 to 9,223,372,036,854,775,807
signed (two's complement) -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
unsigned 0 to 1.84 · 1019 0 to 18,446,744,073,709,551,615
floating
point
32 IEEE-754 ± 3.4 · 10± 38
(~7 digits)
  • min subnormal: ± 1.401,298,4 · 10-47
  • min normal: ± 1.175,494,3 · 10-38
  • max: ± 3.402,823,4 · 1038
64 IEEE-754 ± 1.7 · 10± 308
(~15 digits)
  • min subnormal: ± 4.940,656,458,412 · 10-324
  • min normal: ± 2.225,073,858,507,201,4 · 10-308
  • max: ± 1.797,693,134,862,315,7 · 10308

[编辑] 关键字

bool, true, false, char, wchar_t, char16_t, char32_t, int, short, long, signed, unsigned, float, double

[编辑] 另请参阅