C, C++和C#中的数值类型及其宽度

整型表（C# 参考）

类型	范围	大小
sbyte	-128 到 127	有符号 8 位整数
byte	0 到 255	无符号 8 位整数
char	U+0000 到 U+ffff	16 位 Unicode 字符
short	-32,768 到 32,767	有符号 16 位整数
ushort	0 到 65,535	无符号 16 位整数
int	-2,147,483,648 到 2,147,483,647	有符号 32 位整数
uint	0 到 4,294,967,295	无符号 32 位整数
long	-9,223,372,036,854,775,808 到 9,223,372,036,854,775,807	有符号 64 位整数
ulong	0 到 18,446,744,073,709,551,615	无符号 64 位整数

如果整数表示的值超出了 ulong 的范围，将产生编译错误。

浮点型表（C# 参考）

类型	大致范围	大小	精度
float	±1.5e−45 到 ±3.4e38	32位	7 位
double	±5.0e−324 到 ±1.7e308	64位	15 到 16 位

decimal（C# 参考）

decimal 关键字表示 128 位数据类型。同浮点型相比，decimal 类型具有更高的精度和更小的范围，这使它适合于财务和货币计算。decimal 类型的大致范围和精度如下表所示。

类型	大致范围	精度	.NET Framework 类型
decimal	±1.0×10-28到 ±7.9×1028	28 到 29 位有效位	System.Decimal

默认值表（C# 参考）

值类型	默认值
bool	false
byte	0
char	'/0'
decimal	0.0M
double	0.0D
enum	表达式 (E)0 产生的值，其中 E 为 enum 标识符。
float	0.0F
int	0
long	0L
sbyte	0
short	0
struct	将所有的值类型字段设置为默认值并将所有的引用类型字段设置为 null 时产生的值。
uint	0
ulong	0
ushort	0

内置类型表（C# 参考）

C# 类型	.NET Framework 类型
bool	System.Boolean
byte	System.Byte
sbyte	System.SByte
char	System.Char
decimal	System.Decimal
double	System.Double
float	System.Single
int	System.Int32
uint	System.UInt32
long	System.Int64
ulong	System.UInt64
object	System.Object
short	System.Int16
ushort	System.UInt16
string	System.String

Storage of Basic Types（C）

Sizes of Fundamental Types

Type	Storage
char, unsigned char, signed char	1 byte
short, unsigned short	2 bytes
int, unsigned int	4 bytes
long, unsigned long	4 bytes
float	4 bytes
double	8 bytes
long double	8 bytes

Data Type Ranges（MS C++）

For 32-bit and 64-bit compilers, Microsoft Visual C++ recognizes the types shown in the table below. Note that the following type also have unsigned forms:

• int (unsigned int)
• __int8 (unsigned __int8)
• __int16 (unsigned __int16)
• __int32 (unsigned __int32)
• __int64 (unsigned __int64)
• short (unsigned short)
• long (unsigned long)
• long long (unsigned long long)

Type Name	Bytes	Other Names	Range of Values
int	4	signed	–2,147,483,648 to 2,147,483,647
unsigned int	4	unsigned	0 to 4,294,967,295
__int8	1	char	–128 to 127
unsigned __int8	1	unsigned char	0 to 255
__int16	2	short, short int, signed short int	–32,768 to 32,767
unsigned __int16	2	unsigned short, unsigned short int	0 to 65,535
__int32	4	signed, signed int, int	–2,147,483,648 to 2,147,483,647
unsigned __int32	4	unsigned, unsigned int	0 to 4,294,967,295
__int64	8	long long, signed long long	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
unsigned __int64	8	unsigned long long	0 to 18,446,744,073,709,551,615
bool	1	none	false or true
char	1	none	–128 to 127 by default 0 to 255 when compiled with /J
signed char	1	none	–128 to 127
unsigned char	1	none	0 to 255
short	2	short int, signed short int	–32,768 to 32,767
unsigned short	2	unsigned short int	0 to 65,535
long	4	long int, signed long int	–2,147,483,648 to 2,147,483,647
unsigned long	4	unsigned long int	0 to 4,294,967,295
long long	8	none (but equivalent to __int64)	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
unsigned long long	8	none (but equivalent to unsigned __int64)	0 to 18,446,744,073,709,551,615
enum	varies	none	See Remarks.
float	4	none	3.4E +/- 38 (7 digits)
double	8	none	1.7E +/- 308 (15 digits)
long double	same as double	none	same as double
wchar_t	2	__wchar_t	0 to 65,535