Range (computer programming)#Range as an alternative to iterator

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 integer variable is all the integers from −32,768 to +32,767.

{{Main|Array data type#Indexing notation}}

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, 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, 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).

Another meaning of range in computer science is an alternative to iterator. When used in this sense, range is defined as "a pair of begin/end iterators packed together".{{Cite web

| author = Andrei Alexandrescu

| author-link = Andrei Alexandrescu

| title = Iterators Must Go

| url = https://accu.org/content/conf2009/AndreiAlexandrescu_iterators-must-go.pdf

| date = 6 May 2009

| access-date = 29 July 2014

| publisher = BoostCon 2009

}} 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 C++20,[https://en.cppreference.com/w/cpp/ranges cppreference] Boost C++ Libraries[http://www.boost.org/libs/range/index.html Boost.Range documentation] and the D standard library.[http://dlang.org/phobos/std_range.html D Phobos Runtime Library std.range module]

File:Range UML class.svg

A data type for ranges can be implemented using generics.

Example in C#.

public record Range(T Start, T End) where T : IComparable;

Example in Kotlin.

data class Range>(val start: T, val end: T)

Example in PHP.

readonly class Range {

public function __construct(

public T $start,

public T $end,

) {}

}

Example in Python.

from dataclasses import dataclass

@dataclass

class Range[T]:

start: T

end: T

Rust has a built-in range struct in the standard library in {{Mono|std::ops::Range}}.{{cite web |title=Range in std::ops - Rust |url=https://doc.rust-lang.org/std/ops/struct.Range.html |website=doc.rust-lang.org |access-date=17 October 2024}}

Rust has the {{Mono|..}} and {{Mono|..{{=}}}} operators.

let heartwarming = "heartwarming!".to_string();

let warm = &heartwarming[5..9];

Zig also has the {{Mono|..}} operator.

// To iterate over consecutive integers, use the range syntax.

var sum: usize = 0;

for (0..5) |i| {

sum += i;

}

As does C#,{{cite web|last1=BillWagner|access-date=2025-02-22|title=Explore ranges of data using indices and ranges - C#|url=https://learn.microsoft.com/en-us/dotnet/csharp/tutorials/ranges-indexes|date=14 November 2023|website=learn.microsoft.com}}

string items[] = ["one","two","three","four"];

string first_three_items[] = items[0..2];

F#,{{cite web|access-date=2025-02-22|title=Range Operator|url=https://camilotk.github.io/fsharp-by-example/chapters/range-operator/|date=17 February 2023|website=F# by example}}

[1..4]

// Outputs: [1; 2; 3; 4]

Kotlin,{{cite web|access-date=2025-02-22|title=Ranges and progressions - Kotlin|url=https://kotlinlang.org/docs/ranges.html#progression|website=Kotlin Help}}

for (i in 1..5) print(i)

and Perl.{{cite web|access-date=2025-02-22|title=perlop - Perl expressions: operators, precedence, string literals - Perldoc Browser|url=https://perldoc.perl.org/perlop#Range-Operators|website=perldoc.perl.org}}

for( 1..5) { print }

Python and PHP does not have any range operator but they do have a {{Code|range}} function.{{cite web |title=Built-in Functions |url=https://docs.python.org/3/library/functions.html#func-range |website=Python documentation |publisher=Python Software Foundation |access-date=17 December 2024 |language=en}}{{cite web |title=PHP: range - Manual |url=https://www.php.net/manual/en/function.range.php |publisher=The PHP Documentation Group |access-date=17 December 2024}}

• Interval

{{Reflist}}

{{DEFAULTSORT:Range (Computer Science)}}

Category:Articles with example C Sharp code

Category:Articles with example PHP code

Category:Articles with example Python (programming language) code

Category:Articles with example Rust code

Category:Arrays

Category:Programming constructs

{{Compu-prog-stub}}