Real data type

A real data type is a data type used in a computer program to represent an approximation of a real number. Because the real numbers are not countable, computers cannot represent them exactly using a finite amount of information. Most often, a computer will use a rational approximation to a real number.

## Contents

* 1 Rational numbers
* 2 Fixed-point numbers
* 3 Floating-point numbers
* 4 Decimal numbers

## Rational numbers

Main page: Rational data type

The most general data type for a rational number stores the numerator and denominator as integers.

## Fixed-point numbers

Main page: Fixed-point arithmetic

A fixed-point data type uses the same denominator for all numbers. The denominator is usually a power of two. For example, in a fixed-point system that uses the denominator 65,536 (216), the hexadecimal number 0x12345678 means 0x12345678/65536 or 305419896/65536 or 4660 + 22136/65536 or about 4660.33777.

## Floating-point numbers

Main page: Floating-point arithmetic

A floating-point data type is a compromise between the flexibility of a general rational number data type and the speed of fixed-point arithmetic. It uses some of the bits in the data type to specify a power of two for the denominator. See IEEE Standard for Floating-Point Arithmetic.

## Decimal numbers

Main page: Decimal data type

Similar to fixed-point or floating-point data type, but with a denominator that is a power of 10 instead of a power of 2.

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Data types

Uninterpreted|

* Bit
* Byte
* Trit
* Tryte
* Word
* Bit array

Numeric|

* Arbitrary-precision or bignum
* Complex
* Decimal
* Fixed point
* Floating point
* Double precision
* Extended precision
* Long double
* Octuple precision
* Quadruple precision
* Single precision
* Reduced precision
* Minifloat
* Half precision
* bfloat16
* Integer
* signedness
* Interval
* Rational

Pointer|

* Address
* physical
* virtual
* Reference

Text|

* Character
* String
* null-terminated

Composite|

* Algebraic data type
* generalized
* Array
* Associative array
* Class
* Dependent
* Equality
* Inductive
* Intersection
* List
* Object
* metaobject
* Option type
* Product
* Record or Struct
* Refinement
* Set
* Union
* tagged

Other|

* Boolean
* Bottom type
* Collection
* Enumerated type
* Exception
* Function type
* Opaque data type
* Recursive data type
* Semaphore
* Stream
* Top type
* Type class
* Unit type
* Void

Related
topics|

* Abstract data type
* Data structure
* Generic
* Kind
* metaclass
* Parametric polymorphism
* Primitive data type
* Protocol
* interface
* Subtyping
* Type constructor
* Type conversion
* Type system
* Type theory

See also platform-dependent and independent units of information

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