.NET Type System—Built-in Value Types

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.NET Type System Languages and Type Systems § CLR Type System Value Types § Built-in Value Types Boolean Values Characters Integers Floating-Point Types Special Issues User-Defined Reference Types § User-Defined Object Type Interfaces of Value Types Assignment Compatibility Nested Types Visibility Accessibility Summary

© 2003 Microsoft Corp.

Built-in Value Types

Table 2.1 lists the CLR's built-in value types. In the table, the "CIL Name" column gives the type's name as used in Common Intermediate Language (CIL), which could best be described as the assembly language for the CLR. CIL is described in more detail in Chapter 4, which covers the execution system. The next column, "Base Framework Name," gives the name for the type in the Base Framework. The Base Framework is often referred to as the Framework Class Library (FCL). As the library contains more than just classes, this name is somewhat inaccurate. Chapter 7 covers the Base Framework in more detail.

Table 2.1 CLR Built-in Value Types

CIL Name	Base Framework Name	Description	CLS Support
bool	System.Boolean	Boolean, true or false	Y
char	System.Char	Unicode character	Y
int8	System.SByte	Signed 8-bit integer	N
int16	System.Int16	Signed 16-bit integer	Y
int32	System.Int32	Signed 32-bit integer	Y
int64	System.Int64	Signed 64-bit integer	Y
unsigned int8	System.Byte	Unsigned 8-bit integer	Y
unsigned int16	System.UInt16	Unsigned 16-bit integer	N
unsigned int32	System.UInt32	Unsigned 32-bit integer	N
unsigned int64	System.UInt64	Unsigned 64-bit integer	N
float32	System.Single	IEEE 32-bit floating-point number	Y
float64	System.Double	IEEE 64-bit floating-point number	Y
native int	System.IntPtr equivalent to the machine word size (32 bits on a 32-bit machine, 64 bits on a 64-bit machine)	Signed native integer,	Y
native unsigned int	System.UIntPtr	Unsigned native integer	N

Note that 8-bit integers appear to be named in an inconsistent manner when compared to the other integral types. Normally, the unsigned integers are known as System.UIntX, where X is the size of the integer. With 8-bit integers, however, the signed version is known as System.SByte, where S means signed. This nomenclature is preferred because unsigned bytes are used more frequently than signed bytes are, so the unsigned byte gets the simpler name.