Fundamental Types

Fundamental Types (C++)

 

Fundamental types in C++ are divided into three categories: integral, floating point, and void. Integral types are capable of handling whole numbers. Floating point types are capable of specifying values that may have fractional parts.

The void type describes an empty set of values. No variable of type void can be specified — it is used primarily to declare functions that return no values or to declare generic pointers to untyped or arbitrarily typed data. Any expression can be explicitly converted or cast to type void. However, such expressions are restricted to the following uses:

The following table explains the restrictions on type sizes. These restrictions are independent of the Microsoft implementation.

Fundamental Types of the C++ Language

Category

Type

Contents

Integral

char

Type char is an integral type that usually contains members of the basic execution character set — By default, this is ASCII in Microsoft C++.

The C++ compiler treats variables of type char, signed char, and unsigned char as having different types. Variables of type char are promoted to int as if they are type signed char by default, unless the /J compilation option is used. In this case they are treated as type unsigned char and are promoted to int without sign extension.

 

bool

Type bool is an integral type that can have one of the two values true or false. Its size is unspecified.

 

short

Type short int (or simply short) is an integral type that is larger than or equal to the size of type char, and shorter than or equal to the size of type int.

Objects of type short can be declared as signed short or unsigned short. Signed short is a synonym for short.

 

int

Type int is an integral type that is larger than or equal to the size of type short int, and shorter than or equal to the size of type long.

Objects of type int can be declared as signed int or unsigned int. Signed int is a synonym for int.

 

__int8, __int16, __int32, __int64, __int128

Sized integer __intn, where n is the size, in bits, of the integer variable. (__int8, __int16, __int32, __int64, and __int128 are Microsoft-specific keywords. Not all types are available on all architectures.)

 

long

Type long (or long int) is an integral type that is larger than or equal to the size of type int.

Objects of type long can be declared as signed long or unsigned long. Signed long is a synonym for long.

long long

Larger than an unsigned long.

Objects of type long long can be declared as signed long long or unsigned long long. Signed long long is a synonym for long long.

wchar_t, __wchar_t

A variable of type wchar_t designates a wide-character or multibyte character type. By default, wchar_t is a native type, but you can use /Zc:wchar_t- to make wchar_t a typedef for unsigned short. The __wchar_t type is a Microsoft-specific synonym for the native wchar_t type.

Use the L prefix before a character or string literal to designate the wide-character type.

Floating point

float

Type float is the smallest floating point type.

 

double

Type double is a floating point type that is larger than or equal to type float, but shorter than or equal to the size of type long double.

Microsoft specific: The representation of long double and double is identical. However, long double and double are separate types.

 

long double

Type long double is a floating point type that is larger than or equal to type double.

Microsoft Specific

The following table lists the amount of storage required for fundamental types in Microsoft C++.

Sizes of Fundamental Types

Type

Size

bool, char, unsigned char, signed char, __int8 

1 byte

__int16, short, unsigned short, wchar_t, __wchar_t

2 bytes

float, __int32, int, unsigned int, long, unsigned long 

4 bytes

double, __int64, long double, long long

8 bytes

__int128

16 bytes

END Microsoft Specific

See Data Type Ranges for a summary of the range of values of each type.

For more information about type conversion, see Standard Conversions.

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