MATLAB Programming Fundamentals - MathWorks

Ordinal Token Operator Description Example

\N Match the Nth token. '<(\w+).>.</\1>' captures
tokens for HTML tags, such as
'title' from the text
''.

(?(N)expr1|expr2) If the Nth token is found, then
match expr1. Otherwise, match
expr2.

'Mr(s?)\..*?(?(1)her|his)

\w*' matches text that includes

her when the text begins with Mrs,

or that includes his when the text

begins with Mr.

Named Token Operator Description Example

(?expr) Capture in a named token the
characters that match the enclosed
expression.

'(?<month>\d+)-(?<day>\d+)-

(?<yr>\d+)' creates named

tokens for the month, day, and year

in an input date of the form mm-dd-

yy.

\k Match the token referred to by
name.

'<(?<tag>\w+).*>.*</

\k<tag>>' captures tokens for

HTML tags, such as 'title' from

the text '<title>Some text</

title>'.

(?(name)expr1|
expr2)

If the named token is found, then

match expr1. Otherwise, match

expr2.

'Mr(?<sex>s?)\..*?(?

(sex)her|his) \w*' matches

text that includes her when the text

begins with Mrs, or that includes

his when the text begins with Mr.

NoteIf an expression has nested parentheses, MATLAB captures tokens that correspond

to the outermost set of parentheses. For example, given the search pattern '(and(y|

rew))', MATLAB creates a token for 'andrew' but not for 'y' or 'rew'.

For more information, see “Tokens in Regular Expressions” on page 2-61.

Regular Expressions