Datatype

MACHINE DATA TYPES

All data in computers based on digital electronics is represented as Bit s (alternatives 0 and 1) on the lowest level. The smallest addressable unit of data is a group of bits called a Byte (usually an Octet , which is 8 bits). The unit processed by Machine Code instructions is called a Word (as of 2006, typically 32 or 64 bits). Most instructions interpret the word as a Binary Number , such that a 32-bit word can represent unsigned integer values from 0 to

2^{32}-1

or signed integer values from

-2^{31}

2^{31}-1

. Because of Two's Complement , the machine language and machine don't need to distinguish between these unsigned and signed data types for the most part.

There is specific set of arithmetic instructions that use a different interpretation of the bits in word as a Floating-point number.

PRIMITIVE DATA TYPES

See Also: primitive type

Programming languages provide some primitive data types as basic building blocks for programs and more specialized Composite Type s. Typically primitive data types include various integer, floating-point and string types. Although basic building blocks, Array s, Record s and Reference s for relations between pieces of data might not be included in primitive data types as they can be seen the collection of several primitive values.

NUMBER TYPES

See Also: Numerical tower

COMPOSITE TYPES

See Also: Composite type

DATA STRUCTURES

See Also: Data structure

ABSTRACT TYPES

See Also: Abstract type

SEE ALSO

Type Theory for the mathematical models of types

Type System for different choices in programming language typing

REFERENCES

Luca Cardelli, Peter Wegner. ''On Understanding Types, Data Abstraction, and Polymorphism,'' {Link without Title} from Computing Surveys, (December, 1985)

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Datatype