computer science

Range (computer programming)

Range (computer programming) is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Range (computer programming) rather than just read about it. In short: 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.

Key takeaways

Range (computer programming) belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Range (computer programming) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Range (computer programming) from memory before moving on to harder problems.

Reference excerpt

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 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.

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, 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).

Range as an alternative to iterator 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". 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, Boost C++ Libraries and the D standard library.

Range as a data type

A data type for ranges can be implemented using generics. Example in C#.

Example in Kotlin.

Example in PHP.

Example in Python.

Rust has a built-in range struct in the standard library in std::ops::Range. C++ has a std::ranges library as well since C++20.

Range as a operator Rust has the .. and ..= operators.

Zig also has the .. operator.

As does C#,

F#,

Kotlin,

and Perl.

Python and PHP does not have any range operator but they do have a range function.

Worked examples

Example 1 — a first encounter with Range (computer programming)

Start with the simplest possible case. Write down what Range (computer programming) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Range (computer programming) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Range (computer programming) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Range (computer programming)

In research: Range (computer programming) appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Range (computer programming) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Range (computer programming) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arrays, Computer programming stubs, Programming constructs, so understanding it makes those chapters shorter.
In everyday life: Look for Range (computer programming) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Range (computer programming) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Range (computer programming) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Range (computer programming) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Range (computer programming) in simple terms?

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.

Why does Range (computer programming) matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Range (computer programming)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Range (computer programming).