(See also type for type system overview and the list of typerelated utilities that are provided by the C++ library).
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. std::nullptr_t
Defined in header <cstddef>  

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.
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. 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. The character types are large enough to represent 256 different values (in order to be suitable for storing UTF8 encoded data) (since C++14). 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). Required to be large enough to represent any supported character code point (32 bits on systems that support Unicode. A notable exception is Windows, where wchar_t is 16 bits and holds UTF16 code units) It has the same size, signedness, and alignment as one of the integral types, but is a distinct type.
 (since C++11) 
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). Modifies the 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.
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 
Besides the minimal bit counts, the C++ Standard guarantees that 1 == sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long) <= sizeof(long long)
.
Note: this allows the extreme case in which bytes are sized 64 bits, all types (including char
) are 64 bits wide, and sizeof
returns 1 for every type.
Note: integer arithmetic is defined differently for the signed and unsigned integer types. See arithmetic operators, in particular integer overflows.
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:
64 bit systems:
Other models are very rare. For example, ILP64 (8/8/8: int, long, and pointer are 64bit) only appeared in some early 64bit Unix systems (e.g. Unicos on Cray).
float
 single precision floating point type. Usually IEEE754 32 bit floating point type double
 double precision floating point type. Usually IEEE754 64 bit floating point type long double
 extended precision floating point type. Does not necessarily map to types mandated by IEEE754. Usually 80bit x87 floating point type on x86 and x8664 architectures. Floatingpoint types may support special values:
INFINITY
0.0
. It compares equal to the positive zero, but is meaningful in some arithmetic operations, e.g. 1.0/0.0 == INFINITY
, but 1.0/0.0 == INFINITY
), and for some mathematical functions, e.g. sqrt(std::complex)
std::nan
, NAN
. Note that C++ takes no special notice of signalling NaNs other than detecting their support by std::numeric_limits::has_signaling_NaN
, and treats all NaNs as quiet. Real floatingpoint numbers may be used with arithmetic operators +  / * and various mathematical functions from cmath. Both builtin operators and library functions may raise floatingpoint exceptions and set errno
as described in math_errhandling
.
Floatingpoint expressions may have greater range and precision than indicated by their types, see FLT_EVAL_METHOD
. Floatingpoint expressions may also be contracted, that is, calculated as if all intermediate values have infinite range and precision, see #pragma STDC FP_CONTRACT.
Some operations on floatingpoint numbers are affected by and modify the state of the floatingpoint environment (most notably, the rounding direction).
Implicit conversions are defined between real floating types and integer types.
See Limits of floating point types and std::numeric_limits for additional details, limits, and properties of the floatingpoint types.
The following table provides a reference for the limits of common numeric representations. As the C++ Standard allows any signed integer representation, the table gives both the minimum guaranteed requirements (which correspond to the limits of one's complement or signandmagnitude) and the limits of the most commonly used implementation, two's complement. All popular data models (including all of ILP32, LP32, LP64, LLP64) use two's complement representation, though.
Type  Size in bits  Format  Value range  

Approximate  Exact  
character  8  signed (one's complement)  127 to 127^{[note 1]}  
signed (two's complement)  128 to 127  
unsigned  0 to 255  
16  unsigned  0 to 65535  
32  unsigned  0 to 1114111 (0x10ffff)  
integral  16  signed (one's complement)  ± 3.27 · 10^{4}  32767 to 32767 
signed (two's complement)  32768 to 32767  
unsigned  0 to 6.55 · 10^{4}  0 to 65535  
32  signed (one's complement)  ± 2.14 · 10^{9}  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 · 10^{9}  0 to 4,294,967,295  
64  signed (one's complement)  ± 9.22 · 10^{18}  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 · 10^{19}  0 to 18,446,744,073,709,551,615  
floating point  32  IEEE754  ± 3.4 · 10^{± 38} (~7 digits) 

64  IEEE754  ± 1.7 · 10^{± 308} (~15 digits) 

char
must represent 256 distinct values, bijectively convertible to the values 0..255 of unsigned char
, which may require a wider range of values. Note: actual (as opposed to guaranteed minimal) limits on the values representable by these types are available in <climits>, <cfloat> and std::numeric_limits
.
bool
, true
, false
, char
, wchar_t
, char16_t
, char32_t
, int
, short
, long
, signed
, unsigned
, float
, double
.
C documentation for arithmetic types 
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