computer science

Matching wildcards

Matching wildcards 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 Matching wildcards rather than just read about it. In short: In computer science, an algorithm for matching wildcards (also known as globbing) is useful in comparing text strings that may contain wildcard syntax. Common uses of these algorithms include command-line interfaces, e.g. the Bourne shell or Microsoft Windows command-line or text editor or file manager, as well as the interfaces for some search engines and databases.

Key takeaways

Matching wildcards 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 Matching wildcards to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Matching wildcards from memory before moving on to harder problems.

Reference excerpt

In computer science, an algorithm for matching wildcards (also known as globbing) is useful in comparing text strings that may contain wildcard syntax. Common uses of these algorithms include command-line interfaces, e.g. the Bourne shell or Microsoft Windows command-line or text editor or file manager, as well as the interfaces for some search engines and databases. Wildcard matching is a subset of the problem of matching regular expressions and string matching in general.

The problem A wildcard matcher tests a wildcard pattern p against an input string s. It performs an anchored match; that is, it returns true only when p matches the entirety of s. The pattern can be based on any common syntax (see globbing). However, on Windows, programmers tend to only discuss a simplified syntax supported by the native C runtime:

No escape characters are defined Wildcards: ? matches exactly one occurrence of any character. * matches arbitrarily many (including zero) occurrences of any character. This article mainly discusses the Windows formulation of the problem, unless otherwise stated.

Definition Stated in zero-based indices, the wildcard-matching problem can be defined recursively as:

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Matching wildcards

Start with the simplest possible case. Write down what Matching wildcards 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 Matching wildcards 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 Matching wildcards 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 Matching wildcards

In research: Matching wildcards 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 Matching wildcards 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: Matching wildcards is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer file formats, Computing commands, History of human–computer interaction, so understanding it makes those chapters shorter.
In everyday life: Look for Matching wildcards 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 Matching wildcards in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Matching wildcards 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 Matching wildcards out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Matching wildcards in simple terms?

Why does Matching wildcards 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 Matching wildcards?

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 Matching wildcards.