In
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includin ...
, 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 array is a systematic arrangement of similar objects, usually in rows and columns.
Things called an array include:
{{TOC right
Music
* In twelve-tone and serial composition, the presentation of simultaneous twelve-tone sets such that the ...
.
# An alternative to
iterator
In computer programming, an iterator is an object that enables a programmer to traverse a container, particularly lists. Various types of iterators are often provided via a container's interface. Though the interface and semantics of a given ite ...
.
Range of a variable
The range of a variable is given as the set of possible values that that variable can hold. In the case of an integer, the variable definition is restricted to whole numbers only, and the range will cover every number within its range (including the maximum and minimum). For example, the range of a
signed 16-bit
16-bit microcomputers are microcomputers that use 16-bit microprocessors.
A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...
integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign ( −1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the language ...
variable is all the integers from −32,768 to +32,767.
Range of an array
When an array is numerically indexed, its range is the upper and lower bound of the array. Depending on the environment, a warning, a
fatal exception, or unpredictable behavior will occur if the program attempts to access an array element that is outside the range. In some
programming languages
A programming language is a system of notation for writing computer program, computer programs. Most programming languages are text-based formal languages, but they may also be visual programming language, graphical. They are a kind of computer ...
, such as
C, arrays have a fixed lower bound (zero) and will contain data at each position up to the upper bound (so an array with 5 elements will have a range of 0 to 4). In others, such as
PHP
PHP is a General-purpose programming language, general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementati ...
, an array may have holes where no element is defined, and therefore an array with a range of 0 to 4 will have ''up to'' 5 elements (and a minimum of 2).
Range as an alternative to iterator
Another meaning of ''range'' in computer science is an alternative to
iterator
In computer programming, an iterator is an object that enables a programmer to traverse a container, particularly lists. Various types of iterators are often provided via a container's interface. Though the interface and semantics of a given ite ...
. When used in this sense, range is defined as "a pair of begin/end iterators packed together".
It is argued
that "Ranges are a superior abstraction" (compared to iterators) for several reasons, including better safety.
In particular, such ranges are supported in
Boost C++ Libraries and the
D standard library.
D Phobos Runtime Library std.range module
/ref>
See also
* Interval
References
Programming constructs
Arrays
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