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RegularExpression

Represents a regular expression pattern for string matching.

$ wo 'StringCases["a1b22c", RegularExpression["[0-9]+"]]'
{1, 22}

$ wo 'StringMatchQ["2024-05-01", RegularExpression["\\d{4}-\\d{2}-\\d{2}"]]'
True

$ wo 'StringReplace["one two", RegularExpression["\\s+"] -> "-"]'
one-two

Escaping

The syntax is PCRE, where a backslash before a character that needs no escaping simply means that character. Patterns written by hand often escape liberally, and those escapes are accepted:

$ wo 'StringReplace["a<b", RegularExpression["\\<"] -> "-"]'
a-b

$ wo 'StringMatchQ["50%", RegularExpression["\\d+\\%"]]'
True

An escape that does mean something keeps its meaning — \. still matches only a literal dot:

$ wo 'StringCases["a.b axb", RegularExpression["a\\.b"]]'
{a.b}