noun
regex
REJ-eks
Regex (noun) means a short line of symbols that describes a pattern of text, used to find, check or replace pieces of writing that match that pattern; short for regular expression. Example: “He wrote a regex to pull every date out of the log file.”
noun
1
A short line of symbols that describes a pattern of text, used to find, check or replace pieces of writing that match that pattern; short for regular expression.
"He wrote a regex to pull every date out of the log file."
"A simple regex will tell you whether the field contains only digits."
2
computing The notation itself, taken as a whole: the set of rules by which such patterns are written.
"Regex differs slightly between programming languages, so a pattern that works in one may need adjusting in another."
How to use regex
Learner’s notesIn plain EnglishA pattern that describes what text should look like so a computer can find or check it.
When to use it
Technical and informal; regular expression is the formal term used in documentation.
Memory tip
The plural is usually regexes; regexen appears as a jokey form among programmers.
Trace the full origin ↓
Common pairings
write a regex
regex pattern
match a regex
regex replace
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He wrote a _____ to pull every date out of the log file.
Etymology
A shortening of regular expression.
Synonyms
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Frequently asked questions
What is the difference between a regex and an ordinary search?
An ordinary search looks for the exact characters you typed. A regex describes a shape of text instead, so one pattern can match anything that fits the description, such as any five-digit number or any word ending in ing.
Is regex a programming language?
No. It is a notation for describing text patterns, used inside programming languages, editors and command-line tools. On its own it cannot store values or perform general computation the way a programming language can.
How is regex pronounced?
Most commonly REJ-eks, with a soft g, although REG-eks with a hard g is also heard. Both are widely understood, and the full form regular expression is unambiguous.
What is the meaning of regex?
"regex" (noun) means a short line of symbols that describes a pattern of text, used to find, check or replace pieces of writing that match that pattern; short for regular expression.
