Programming and Data Types 

Regular Expressions
There are several MATLAB functions that support searching and replacing characters using regular expressions. These functions are
The following tables list the regular expression syntax supported by MATLAB. This list is not intended to be a complete reference. For more information on regular expressions and their meanings, consult a reference on regular expressions.
Note
Any character appearing in a regular expression is ordinary, unless a '\' precedes it.

This section contains the following topics:
Metacharacters
Metacharacters don't match themselves but describe something else. Generally they represent groups of characters or keyboard keys without a representative character.
Expression

Usage

.

Matches any single character

[ab...]

Matches any one of the characters, (a , b , etc.), contained within the brackets

[^ab...]

Matches any character except those contained within the brackets, (a , b , etc.).

[c _{1}c _{2}]

Matches any characters in the range of c _{1} through c _{2.}

\f

Form feed.

\n

New line.

\r

Carriage return.

\t

Tab.

\d

A digit. Equivalent regular expression: [09]

\D

A nondigit. Equivalent regular expression: [^09]

\s

A whitespace character. Equivalent regular expression: [ \f\n\r\t]

\S

A nonwhitespace character. Equivalent regular expression: [^ \f\n\r\t]

\w

A word character. Equivalent regular expression: [azAZ_09]

\W

A nonword character. Equivalent regular expression: [^azAZ_09]

\

If a character has special meaning in a regular expression, precede it with this character to match it literally.

Logical Operators
Logical operators do not match any specific characters. They are used to specify the context for matching an accompanying regular expression.
Expression

Usage

(...)

Groups regular expressions.



Matches either the expression preceding or following it.

^

Matches following expression only at the beginning of the string.

$

Matches preceding expression only at the end of the string.

\<chars

Matches the characters when they start a word.

chars\>

Matches the characters when they end a word.

\<word\>

Exact word match.

Quantifiers
Quantifiers are a type of logical operator. They are used to specify how many instances of the previous element they can match.
Expression

Usage

*

Matches the preceding element 0 or more times. Equivalent regular expression: {0,}

+

Matches the preceding element 1 or more times. Equivalent regular expression: {1,}

?

Matches the preceding element 0 times or 1 time, also minimizes. Equivalent regular expression: {0,1}

{n,m}

Must occur at least n times but no more than m times

{n,}

Must occur at least n times.

{n}

Must match exactly n times. Equivalent regular expression: {n,n}

 Searching and Replacing   Searching with Tokens  