Primitive type
Encyclopedia
In computer science
, primitive data type is either of the following:
In most programming languages, all basic data types are built-in. In addition, many languages also provide a set of composite data types. Opinions vary as to whether a built-in type that is not basic should be considered "primitive".
Depending on the language and its implementation, primitive data types may or may not have a one-to-one correspondence with objects in the computer's memory. However, one usually expects operations on basic primitive data types to be the fastest language constructs there are. Integer addition, for example, can be performed as a single machine instruction, and some processors
offer specific instructions to process sequences of characters with a single instruction. In particular, the C
standard mentions that "a'plain' int object has the natural size suggested by the architecture of the execution environment". This means that
s.
Most languages do not allow the behavior or capabilities of primitive (either built-in or basic) data types to be modified by programs. Exceptions include Smalltalk
, which permits all data types to be extended within a program, adding to the operations that can be performed on them or even redefining the built-in operations.
, strings
are a composite but built-in data type, whereas in modern dialects of BASIC
and in JavaScript
, they are assimilated to a primitive data type that is both basic and built-in.
Classic basic primitive types may include:
More sophisticated types which can be built-in include:
Literals for integers consist of a sequence of digits. Most programming languages disallow use of commas for digit grouping, although Fortran
(77, 90, and above, fixed form source but not free form source) allows embedded spaces, and Perl
, Ruby
, and D
allow embedded underscore
s. Negation is indicated by a minus sign (−) before the value. Examples of integer literals are:
type, typically denoted "bool" or "boolean", is typically a logical type that can be either "true" or "false". Although only one bit is necessary to accommodate the value set "true" and "false", programming languages typically implement boolean types as one or more bytes.
Most languages (Java
, Pascal
and Ada
, e.g.) implement booleans adhering to the concept of boolean as a distinct logical type. Languages, though, may implicitly convert booleans to numeric types at times to give extended semantics to booleans and boolean expressions or to achieve backwards compatibility with earlier versions of the language. In C++
, e,g., boolean values may be implicitly converted to integers, according to the mapping false → 0 and true → 1 (for example,
that may have a fractional part. These numbers are stored internally in a format equivalent to scientific notation
, typically in binary
but sometimes in decimal
. Because floating-point numbers have limited precision, only a subset of real
or rational
numbers are exactly representable; other numbers can be represented only approximately.
Many languages have both a single precision (often called "float") and a double precision
type.
Literals for floating point numbers include a decimal point, and typically use "e" or "E" to denote scientific notation. Examples of floating-point literals are:
Some languages (e.g., Fortran
, Python
, D
) also have a complex number
type comprising two floating-point numbers: a real part and an imaginary part.
number represents a limited-precision rational number
that may have a fractional part. These numbers are stored internally in a scaled-integer form, typically in binary
but sometimes in decimal
. Because fixed-point numbers have limited precision, only a subset of real
or rational
numbers are exactly representable; other numbers can be represented only approximately. Fixed-point numbers also tend to have a more limited range of values than floating point
, and so the programmer must be careful to avoid overflow in intermediate calculations as well as the final results.
type (typically called "char") may contain a single letter
, digit
, punctuation mark, symbol
, formatting code, control code, or some other specialized code (e.g., a byte order mark
). Some languages have two or more character types, for example a single-byte type for ASCII
characters and a multi-byte type for Unicode
characters. The term "character type" is normally used even for types whose values more precisely represent code units, for example a UTF-16 code unit as in Java
and JavaScript
.
Characters may be combined into strings
. The string data can include numbers and other numerical symbols but will be treated as text.
In most languages, a string is equivalent to an array of characters or code units, but Java
treats them as distinct types (
, and many dialects of BASIC
) have no separate character type; strings with a length of one are normally used to represent (single code unit) characters.
Literals for characters and strings are usually surrounded by quotation marks: sometimes, single quotes (') are used for characters and double quotes (") are used for strings.
Examples of character literals in C syntax are:
Examples of string literals in C syntax are:
. Attempting to store a number outside the range may lead to compiler/runtime errors, or to incorrect calculations (due to truncation
) depending on the language being used.
The range of a variable is based on the number of bytes used to save the value, and an integer data type is usually able to store
values (where 
is the number of bit
s that contribute to the value). For other data types (e.g. floating point
values) the range is more complicated and will vary depending on the method used to store it. There are also some types that do not use entire bytes, e.g. a boolean that requires a single bit
, and represents a binary
value (although in practice a byte is often used, with the remaining 7 bits being redundant). Some programming languages (such as Ada
and Pascal
) also allow the opposite direction, that is, the programmer defines the range and precision needed to solve a given problem and the compiler chooses the most appropriate integer or floating point type automatically.
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, primitive data type is either of the following:
- a basic type is a data typeData typeIn computer programming, a data type is a classification identifying one of various types of data, such as floating-point, integer, or Boolean, that determines the possible values for that type; the operations that can be done on values of that type; the meaning of the data; and the way values of...
provided by a programming languageProgramming languageA programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
as a basic building block. Most languages allow more complicated composite typeComposite typeIn computer science, a composite data type is any data type which can be constructed in a program using its programming language's primitive data types and other composite types...
s to be recursively constructed starting from basic types. - a built-in type is a data type for which the programming language provides built-in support.
In most programming languages, all basic data types are built-in. In addition, many languages also provide a set of composite data types. Opinions vary as to whether a built-in type that is not basic should be considered "primitive".
Depending on the language and its implementation, primitive data types may or may not have a one-to-one correspondence with objects in the computer's memory. However, one usually expects operations on basic primitive data types to be the fastest language constructs there are. Integer addition, for example, can be performed as a single machine instruction, and some processors
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
offer specific instructions to process sequences of characters with a single instruction. In particular, the C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
standard mentions that "a
int is likely to be 32 bits long on a 32-bit architecture. Basic primitive types are almost always value typeValue type
In computer science, the term value type is commonly used to refer to one of two kinds of data types: Types of values or Types of objects with deep copy semantics.- Types of Values :...
s.
Most languages do not allow the behavior or capabilities of primitive (either built-in or basic) data types to be modified by programs. Exceptions include Smalltalk
Smalltalk
Smalltalk is an object-oriented, dynamically typed, reflective programming language. Smalltalk was created as the language to underpin the "new world" of computing exemplified by "human–computer symbiosis." It was designed and created in part for educational use, more so for constructionist...
, which permits all data types to be extended within a program, adding to the operations that can be performed on them or even redefining the built-in operations.
Overview
The actual range of primitive data types that is available is dependent upon the specific programming language that is being used. For example, in CC (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, strings
String (computer science)
In formal languages, which are used in mathematical logic and theoretical computer science, a string is a finite sequence of symbols that are chosen from a set or alphabet....
are a composite but built-in data type, whereas in modern dialects of BASIC
BASIC
BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
and in JavaScript
JavaScript
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
, they are assimilated to a primitive data type that is both basic and built-in.
Classic basic primitive types may include:
- CharacterCharacter (computing)In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....
(character,char); - IntegerInteger (computer science)In computer science, an integer is a datum of integral data type, a data type which represents some finite subset of the mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values....
(integer,int,short,long,byte) with a variety of precisionsPrecision (computer science)In computer science, precision of a numerical quantity is a measure of the detail in which the quantity is expressed. This is usually measured in bits, but sometimes in decimal digits. It is related to precision in mathematics, which describes the number of digits that are used to express a...
; - Floating-point numberFloating pointIn computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
(float,double,real,double precision); - Fixed-point numberFixed-point arithmeticIn computing, a fixed-point number representation is a real data type for a number that has a fixed number of digits after the radix point...
(fixed) with a variety of precisionsPrecision (computer science)In computer science, precision of a numerical quantity is a measure of the detail in which the quantity is expressed. This is usually measured in bits, but sometimes in decimal digits. It is related to precision in mathematics, which describes the number of digits that are used to express a...
and a programmer-selected scaleOrder of magnitudeAn order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...
. - Boolean, logical values true and false.
- ReferenceReference (computer science)In computer science, a reference is a value that enables a program to indirectly access a particular data item, such as a variable or a record, in the computer's memory or in some other storage device. The reference is said to refer to the data item, and accessing those data is called...
(also called a pointer or handle), a small value referring to another object's address in memory, possibly a much larger one.
More sophisticated types which can be built-in include:
- TupleTupleIn mathematics and computer science, a tuple is an ordered list of elements. In set theory, an n-tuple is a sequence of n elements, where n is a positive integer. There is also one 0-tuple, an empty sequence. An n-tuple is defined inductively using the construction of an ordered pair...
s in ML, PythonPython (programming language)Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive... - Linked listLinked listIn computer science, a linked list is a data structure consisting of a group of nodes which together represent a sequence. Under the simplest form, each node is composed of a datum and a reference to the next node in the sequence; more complex variants add additional links...
s in Lisp - Complex numberComplex numberA complex number is a number consisting of a real part and an imaginary part. Complex numbers extend the idea of the one-dimensional number line to the two-dimensional complex plane by using the number line for the real part and adding a vertical axis to plot the imaginary part...
s in FortranFortranFortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
, C (C99)C99C99 is a modern dialect of the C programming language. It extends the previous version with new linguistic and library features, and helps implementations make better use of available computer hardware and compiler technology.-History:...
, Lisp, PythonPython (programming language)Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, Perl 6Perl 6Perl 6 is a major revision to the Perl programming language. It is still in development, as a specification from which several interpreter and compiler implementations are being written. It is introducing elements of many modern and historical languages. Perl 6 is intended to have many...
, DD (programming language)The D programming language is an object-oriented, imperative, multi-paradigm, system programming language created by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is mainly influenced by that language, it is not a variant of C++... - Rational numberRational numberIn mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every integer is a rational number...
s in Lisp, Perl 6Perl 6Perl 6 is a major revision to the Perl programming language. It is still in development, as a specification from which several interpreter and compiler implementations are being written. It is introducing elements of many modern and historical languages. Perl 6 is intended to have many... - Hash tableHash tableIn computer science, a hash table or hash map is a data structure that uses a hash function to map identifying values, known as keys , to their associated values . Thus, a hash table implements an associative array...
s in various guises, in Lisp, PerlPerlPerl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
, PythonPython (programming language)Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, Lua, DD (programming language)The D programming language is an object-oriented, imperative, multi-paradigm, system programming language created by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is mainly influenced by that language, it is not a variant of C++... - First-class functionFirst-class functionIn computer science, a programming language is said to have first-class functions if it treats functions as first-class objects. Specifically, this means that the language supports passing functions as arguments to other functions, returning them as the values from other functions, and assigning...
s, closures, continuationContinuationIn computer science and programming, a continuation is an abstract representation of the control state of a computer program. A continuation reifies the program control state, i.e...
s in languages that support functional programmingFunctional programmingIn computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state...
such as Lisp, ML, Perl 6Perl 6Perl 6 is a major revision to the Perl programming language. It is still in development, as a specification from which several interpreter and compiler implementations are being written. It is introducing elements of many modern and historical languages. Perl 6 is intended to have many...
, DD (programming language)The D programming language is an object-oriented, imperative, multi-paradigm, system programming language created by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is mainly influenced by that language, it is not a variant of C++...
and C# 3.0C Sharp 3.0The programming language C# version 3.0 was released on 19 November 2007 as part of .NET Framework 3.5. It includes new features inspired by functional programming languages such as Haskell and ML, and is driven largely by the introduction of the Language Integrated Query pattern to the Common...
Integer numbers
An integer data type can hold a whole number, but no fraction. Integers may be either signed (allowing negative values) or unsigned (nonnegative values only). Typical sizes of integers are:| Size | Names | Signed Range | Unsigned Range |
|---|---|---|---|
| 8 bits | Byte Byte The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer... |
−128 to +127 | 0 to 255 |
| 16 bits | Word, short int | −32,768 to +32,767 | 0 to 65,535 |
| 32 bits | Double Word, long int (win32, win64, 32-bit Linux) | −2,147,483,648 to +2,147,483,647 | 0 to 4,294,967,295 |
| 64 bits | long int (C in 64-bit linux), long long (C C (programming language) C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system.... ), long (Java Java (programming language) Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities... , the signed integer variant only)) |
−9,223,372,036,854,775,808 to +9,223,372,036,854,775,807 | 0 to 18,446,744,073,709,551,615 |
| unlimited | Bignum |
Literals for integers consist of a sequence of digits. Most programming languages disallow use of commas for digit grouping, although Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
(77, 90, and above, fixed form source but not free form source) allows embedded spaces, and Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
, Ruby
Ruby (programming language)
Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto...
, and D
D (programming language)
The D programming language is an object-oriented, imperative, multi-paradigm, system programming language created by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is mainly influenced by that language, it is not a variant of C++...
allow embedded underscore
Underscore
The underscore [ _ ] is a character that originally appeared on the typewriter and was primarily used to underline words...
s. Negation is indicated by a minus sign (−) before the value. Examples of integer literals are:
- 42
- 10000
- −233000
Booleans
A booleanBoolean datatype
In computer science, the Boolean or logical data type is a data type, having two values , intended to represent the truth values of logic and Boolean algebra...
type, typically denoted "bool" or "boolean", is typically a logical type that can be either "true" or "false". Although only one bit is necessary to accommodate the value set "true" and "false", programming languages typically implement boolean types as one or more bytes.
Most languages (Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
, Pascal
Pascal (programming language)
Pascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...
and Ada
Ada (programming language)
Ada is a structured, statically typed, imperative, wide-spectrum, and object-oriented high-level computer programming language, extended from Pascal and other languages...
, e.g.) implement booleans adhering to the concept of boolean as a distinct logical type. Languages, though, may implicitly convert booleans to numeric types at times to give extended semantics to booleans and boolean expressions or to achieve backwards compatibility with earlier versions of the language. In C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, e,g., boolean values may be implicitly converted to integers, according to the mapping false → 0 and true → 1 (for example,
true + true would be a valid expression evaluating to 2). The boolean type bool in C++ is considered an integral type and is a cross between numeric type and a logical type.Floating-point numbers
A floating-point number represents a limited-precision rational numberRational number
In mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every integer is a rational number...
that may have a fractional part. These numbers are stored internally in a format equivalent to scientific notation
Scientific notation
Scientific notation is a way of writing numbers that are too large or too small to be conveniently written in standard decimal notation. Scientific notation has a number of useful properties and is commonly used in calculators and by scientists, mathematicians, doctors, and engineers.In scientific...
, typically in binary
Binary numeral system
The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...
but sometimes in decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....
. Because floating-point numbers have limited precision, only a subset of real
Real number
In mathematics, a real number is a value that represents a quantity along a continuum, such as -5 , 4/3 , 8.6 , √2 and π...
or rational
Rational number
In mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every integer is a rational number...
numbers are exactly representable; other numbers can be represented only approximately.
Many languages have both a single precision (often called "float") and a double precision
Double precision
In computing, double precision is a computer number format that occupies two adjacent storage locations in computer memory. A double-precision number, sometimes simply called a double, may be defined to be an integer, fixed point, or floating point .Modern computers with 32-bit storage locations...
type.
Literals for floating point numbers include a decimal point, and typically use "e" or "E" to denote scientific notation. Examples of floating-point literals are:
- 20.0005
- 99.9
- −5000.12
- 6.02e23
Some languages (e.g., Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
, Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, D
D (programming language)
The D programming language is an object-oriented, imperative, multi-paradigm, system programming language created by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is mainly influenced by that language, it is not a variant of C++...
) also have a complex number
Complex number
A complex number is a number consisting of a real part and an imaginary part. Complex numbers extend the idea of the one-dimensional number line to the two-dimensional complex plane by using the number line for the real part and adding a vertical axis to plot the imaginary part...
type comprising two floating-point numbers: a real part and an imaginary part.
Fixed-point numbers
A fixed-pointFixed-point arithmetic
In computing, a fixed-point number representation is a real data type for a number that has a fixed number of digits after the radix point...
number represents a limited-precision rational number
Rational number
In mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every integer is a rational number...
that may have a fractional part. These numbers are stored internally in a scaled-integer form, typically in binary
Binary numeral system
The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...
but sometimes in decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....
. Because fixed-point numbers have limited precision, only a subset of real
Real number
In mathematics, a real number is a value that represents a quantity along a continuum, such as -5 , 4/3 , 8.6 , √2 and π...
or rational
Rational number
In mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every integer is a rational number...
numbers are exactly representable; other numbers can be represented only approximately. Fixed-point numbers also tend to have a more limited range of values than floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
, and so the programmer must be careful to avoid overflow in intermediate calculations as well as the final results.
Characters and strings
A characterCharacter (computing)
In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....
type (typically called "char") may contain a single letter
Letter (alphabet)
A letter is a grapheme in an alphabetic system of writing, such as the Greek alphabet and its descendants. Letters compose phonemes and each phoneme represents a phone in the spoken form of the language....
, digit
Numerical digit
A digit is a symbol used in combinations to represent numbers in positional numeral systems. The name "digit" comes from the fact that the 10 digits of the hands correspond to the 10 symbols of the common base 10 number system, i.e...
, punctuation mark, symbol
Symbol
A symbol is something which represents an idea, a physical entity or a process but is distinct from it. The purpose of a symbol is to communicate meaning. For example, a red octagon may be a symbol for "STOP". On a map, a picture of a tent might represent a campsite. Numerals are symbols for...
, formatting code, control code, or some other specialized code (e.g., a byte order mark
Byte Order Mark
The byte order mark is a Unicode character used to signal the endianness of a text file or stream. Its code point is U+FEFF. BOM use is optional, and, if used, should appear at the start of the text stream...
). Some languages have two or more character types, for example a single-byte type for ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
characters and a multi-byte type for Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
characters. The term "character type" is normally used even for types whose values more precisely represent code units, for example a UTF-16 code unit as in Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
and JavaScript
JavaScript
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
.
Characters may be combined into strings
String (computer science)
In formal languages, which are used in mathematical logic and theoretical computer science, a string is a finite sequence of symbols that are chosen from a set or alphabet....
. The string data can include numbers and other numerical symbols but will be treated as text.
In most languages, a string is equivalent to an array of characters or code units, but Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
treats them as distinct types (
java.lang.String and char[]). Other languages (such as PythonPython (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, and many dialects of BASIC
BASIC
BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
) have no separate character type; strings with a length of one are normally used to represent (single code unit) characters.
Literals for characters and strings are usually surrounded by quotation marks: sometimes, single quotes (') are used for characters and double quotes (") are used for strings.
Examples of character literals in C syntax are:
- 'A'
- '4'
- '$'
- '\t' (tab characterTab keyTab key on a keyboard is used to advance the cursor to the next tab stop.- Origin :The word tab derives from the word tabulate, which means "to arrange data in a tabular, or table, form"...
)
Examples of string literals in C syntax are:
- "A"
- "Hello World"
Numeric data type ranges
Each numeric data type has its maximum and minimum value known as the rangeRange (computer science)
In computer science, the term range may refer to one of three things:# The possible values that may be stored in a variable.# The upper and lower bounds of an array.# An alternative to iterator.-Range of a variable:...
. Attempting to store a number outside the range may lead to compiler/runtime errors, or to incorrect calculations (due to truncation
Truncation
In mathematics and computer science, truncation is the term for limiting the number of digits right of the decimal point, by discarding the least significant ones.For example, consider the real numbersThe result would be:- Truncation and floor function :...
) depending on the language being used.
The range of a variable is based on the number of bytes used to save the value, and an integer data type is usually able to store
values (where is the number of bitBit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s that contribute to the value). For other data types (e.g. floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
values) the range is more complicated and will vary depending on the method used to store it. There are also some types that do not use entire bytes, e.g. a boolean that requires a single bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
, and represents a binary
Binary numeral system
The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...
value (although in practice a byte is often used, with the remaining 7 bits being redundant). Some programming languages (such as Ada
Ada (programming language)
Ada is a structured, statically typed, imperative, wide-spectrum, and object-oriented high-level computer programming language, extended from Pascal and other languages...
and Pascal
Pascal (programming language)
Pascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...
) also allow the opposite direction, that is, the programmer defines the range and precision needed to solve a given problem and the compiler chooses the most appropriate integer or floating point type automatically.
See also
- List of data structures: Data types
- Primitive wrapper classPrimitive wrapper classA primitive wrapper class in the Java programming language is one of eight classes provided in the package to provide object methods for the eight primitive types. All of the primitive wrapper classes in Java are immutable...
- Object typeObject typeIn computer science, an object type is a datatype which is used in object-oriented programming to wrap a non-object type to make it look like a dynamic object....
- Language primitiveLanguage primitiveIn computing, language primitives are the simplest elements available in a programming language. A primitive can be defined as the smallest 'unit of processing' available to a programmer of a particular machine, or can be an atomic element of an expression in a language.-Machine level primitives:A...