Regexp - Assertion (Condition)

Regexp

Regexp - Assertion (Condition)

About

An assertion is an assertion that specifies a condition that has to be met at a particular point in a match, without consuming any characters from the subject string.

Type

Simple

simple assertion designed by the backslash character.

assertions Description
\b word boundary
\B not a word boundary
\A start of subject (independent of multiline mode)
\Z end of subject or newline at end (independent of multiline mode)
\z end of subject (independent of multiline mode)
\G first matching position in subject

These assertions may not appear in character classes (but note that “\b” has a different meaning, namely the backspace character, inside a character class).

Look-around

Regexp - Look-around group (Assertion) - ( Lookahead | Lookbehind )





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