Data type

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Data Type

In computer science and computer programming, data type is a set of possible values and a set of allowed operations on it. A data type tells the compiler or interpreter how the programmer intends to use the data.

Concept

A data type is a collection or grouping of data values. Such a grouping may be defined for many reasons: similarity, convenience, or to focus the attention.

  • Primitive types
  • Composite types or non-primitive type
  • Abstract data types

Notable data types

Machine data types

All data based on digital electronics is represented a bits on the lowest level.

Boolean type

Represents the true and false.

Numeric types

Integer data types.

Enumerations

The enumerated type has distinct values, which can be compared and assigned, but which do not necessarily have any particular concrete representation in the computer’s memory.

String and text types

Strings are a sequence of characters used to store words or plain text, most often textual markup languages representing formatted text.

Union types

A tagged union(also called a variant) contains an additional field indicating its current type for enhanced type safety.

Algebraic data types

An ADT is a possibly recursive sum type of product types.

Data structures

Some types are very useful for storing and retrieving data and are called data structures. Common data structures include:

  • An array(also called vector, list or sequence) stores a number of elements and provides random access to individual elements.
    • Typically required to be the same type
    • May be fixed-length or expandable
    • Indices into an array are typically required to be integers
  • Record(also called tuple or struct)
    • simplest
    • typically indexed by names
    • typically in fixed number and sequence

  • An object contains a number of data fields, like record, and also a number of subroutines for accessing or modifying them, called methods

  • Singly linked list
    • Implementing a queue and it defined in Haskell as the ADT(Abstract data types)
  • Binary tree
    • allowing fast searching
    • can be defined in Haskell as the ADT

Abstract data types

An abstract data type is a data type that does not specify the concrete representation of the data. Instead, a formal specification based on the data type’s operations is used to describe it. Any implementation of a specification must fulfill the rules given.

Pointers and references

A data type whose value refers directly to another values stored elsewhere in the computer memory using its address. If the value of pointer was never a valid memory address would cause a program to crash. This is an potential problem.

Others

  • Function types
  • Type constructors
  • Quantified types
  • Refinement types
  • Dependent types
  • Meta types
  • Convenience types

Source

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