MATLAB Programming Fundamentals - MathWorks

Quantifier Matches the expression when it
occurs...

Example

expr{m,} At least m times consecutively.

{0,} and {1,} are equivalent to * and

+, respectively.

'<a href="\w{1,}\.html">' matches

an <a> HTML tag when the file name

contains one or more characters.

expr{n} Exactly n times consecutively.

Equivalent to {n,n}.

'\d{4}' matches four consecutive digits.

Quantifiers can appear in three modes, described in the following table. q represents any

of the quantifiers in the previous table.

Mode Description Example

exprq Greedy expression: match as many
characters as possible.

Given the text

'<tr><td><p>text</p></td>', the

expression '</?t.*>' matches all

characters between <tr and /td>:

'<tr><td><p>text</p></td>'

exprq? Lazy expression: match as few
characters as necessary.

Given the

text'<tr><td><p>text</p></td>',

the expression '</?t.*?>' ends each

match at the first occurrence of the

closing angle bracket (>):

'<tr>' '<td>' '</td>'

exprq+ Possessive expression: match as much as
possible, but do not rescan any portions
of the text.

Given the

text'<tr><td><p>text</p></td>',

the expression '</?t.*+>' does not

return any matches, because the closing

angle bracket is captured using .*, and

is not rescanned.

Grouping Operators

Grouping operators allow you to capture tokens, apply one operator to multiple elements,

or disable backtracking in a specific group.

Regular Expressions